The Best Laundry Detergent

We are currently testing an array of laundry detergents.

Laundry detergent promises cleaner clothing through science: These extraordinarily complex goos and powders have to remove dirt, stains, and odors from fabric, and then rinse away without damaging your clothes, your washer, your skin, or the environment. We pitted 17 detergents against 10 common stains in cold water, and we found that Tide Ultra Stain Release was more effective at lifting a wider variety of stains than the competition.

This liquid laundry detergent was a top performer in our stain testing, lifting more of a wider variety of stains than any other detergent we tried.

Although a few detergents we tried did better on specific stains, Tide Ultra Stain Release was consistently a top performer, and it removed more blood, sebum, and cocoa than any other detergent we tested. It also did a good job of getting bacon smells out in our odor testing. We like the dye- and scent-free version, as well, although its formula is not identical to that of our pick.

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Persil was one of the most effective stain removers in our testing, and it even bested our main pick on several stains. But its strong, lingering fragrance is not for everyone.

Persil ProClean Stain Fighter performed nearly as well as Tide Ultra Stain Release in our tests. And the Persil even beat the Tide detergent when it was used on browned butter, foundation makeup, and spaghetti sauce. One of Persil’s defining features is its intense fragrance, which can last for days on clothes and which some people find overwhelming.

This detergent, sold under Costco’s house brand, was better at removing stains than many more-expensive detergents, and it is also good at getting rid of odors.

Costco’s house-brand detergent, Kirkland Signature Ultra Clean, cleaned almost as well overall as Tide Ultra Stain Release and Persil ProClean Stain Fighter in our stain testing, and it costs about half as much. Although none of the detergents were able to remove makeup that effectively, Kirkland did a significantly better job than the rest. It was also one of the best at removing odors.

This dye- and scent-free detergent is one of the most effective stain and odor removers we’ve tested.

If you prefer a detergent that doesn’t have dyes or fragrance, Tide Ultra Stain Release Free is great at getting out stains and odors without leaving a scent behind. But it’s available only at Target.

This liquid laundry detergent was a top performer in our stain testing, lifting more of a wider variety of stains than any other detergent we tried.

Persil was one of the most effective stain removers in our testing, and it even bested our main pick on several stains. But its strong, lingering fragrance is not for everyone.

This detergent, sold under Costco’s house brand, was better at removing stains than many more-expensive detergents, and it is also good at getting rid of odors.

This dye- and scent-free detergent is one of the most effective stain and odor removers we’ve tested.

We interviewed many experts for this guide, including Brian Grady, PhD, the director of the Institute for Applied Surfactant Research at the University of Oklahoma (and a project engineer at Procter & Gamble from 1987 to 1989); Sol Escobar, a biomedical engineer with Procter & Gamble; Mary Johnson and Jennifer Ahoni, scientific communication managers with Procter & Gamble (P&G is the parent company of many detergent brands, including Tide, Gain, Cheer, Dreft, and Era); Cory Dunnick, MD, a board-certified dermatologist and associate professor and director of the Dermatitis and Contact Allergy Clinic at the University of Colorado; Katie Jennings, a formulation scientist with Seventh Generation; and Jonathan Propper, founder and CEO of Dropps. We also toured the testing facility at Procter & Gamble in Cincinnati.

In addition, we read numerous laundry detergent guides, including those from Good Housekeeping, Consumer Reports, CNET, Reviewed, and The Spruce.

Sarah Bogdan has tested 57 laundry detergents in her career thus far, previously for Good Housekeeping and now for Wirecutter. She has also tested washing machines and dryers, so she’s done a lot of laundry. Sarah has also played rugby for several years, and so she’s seen an above-average amount of mud, grass, and blood stains, all of which she’s successfully gotten out herself.

Leigh Krietsch Boerner, a former Wirecutter staffer who wrote the original version of this guide, is a PhD chemist with a working background in textiles.

There are three main types of laundry detergent: liquid, powder, and pods (called “unit-doses” by the industry, they’re also known as “packs,” “discs,” “single-dose,” or “tablets”). For this round of testing, we decided to focus solely on liquid laundry detergents. Not only did they perform better than powders and pods in our last round of testing, but they also account for the majority of what’s sold. Procter & Gamble told us that, according to a Nielsen report of sales from 2019 and 2020, 73% of products in the laundry category are liquid, 20% are pods, and 7% are powders. Liquid detergents are popular for a variety of reasons. One of their big advantages is that, unlike powder detergent and pods, they’re pre-dissolved. If you have ever started a load of laundry, walked away, and come back to find clumps of powder detergent or an undissolved pod among wet, dirty laundry, you can probably appreciate how foolproof liquid detergent is. (Powder can have an especially hard time dissolving in cold-water washes.) Liquid detergent can also be used directly for pretreating stains.

Pods are growing in popularity, not least because of their convenience—you don’t have to carry a heavy, bulky jug around or measure anything out. The downsides, however, are that unless you’re careful to weigh out or eyeball the size of your load before tossing in the recommended number of pods, you’re likely to use too little or too much detergent. They’re too concentrated for handwashing or pretreating, and they pose a safety hazard to children and to those who have cognitive issues or dementia. They’re also relatively expensive, costing as much as 25% to 50% more per load.

In addition to pods, unit-dose strips or sheets, which are meant to offer the same convenience as pods and also to reduce packaging waste, have recently been introduced by companies. Based on conversations with detergent experts, we’re skeptical that they’ll be as effective as liquid detergent, but we plan on testing them in the future.

We didn’t look at specialty detergents—those with additives like fabric softener or oxygen bleach, those formulated for specific textiles or colors, or those designated for babies—because most people don’t need them.

In fact, some of those additives can actually be an impediment to getting your clothes clean. Detergents that include fabric softeners, for example, should not be used to clean workout clothes, towels, or children’s pajamas. The residue they leave, which is what softens the fabric, can block pores in certain materials, reducing their ability to wick away moisture. As a result, workout clothes might actually retain moisture, making you uncomfortable and stinky. That residue also makes it harder for towels to absorb water and can lock in odor, and can be the reason they start to smell mildewy. Fabric softener also reduces the effectiveness of flame retardant, which is key to making many children’s pajamas flame-resistant, as required by law.

We eliminated detergents with oxygen bleach because you can add something like OxiClean separately, as needed. Because we were focusing on general-purpose detergents, we did not consider detergents made specifically to care for wool, cashmere, or silk or those formulated for black or colors. We did not look at detergents specially formulated for babies because, according to the American Academy of Pediatrics, many parents say their babies aren’t affected by having their clothes washed with regular detergent.

We looked primarily at detergents that were formulated for high-efficiency (HE) washers because HE detergents work in both HE machines and in older, non-HE machines. But non-HE detergents should never be used in HE machines, because the formulas suds up too much in that environment (see HE vs. regular detergents). Most detergents sold are HE detergents.

In addition, we read and compared laundry detergent reviews from Good Housekeeping, Reviewed, CNET, and The Spruce, and pored over the user reviews for detergents available on Amazon, Target, and Walmart.

After narrowing down our list based on the considerations above, we were left with 17 liquid laundry detergents.

To test how effective the detergents were at cleaning, we did many, many loads of laundry, pitting each detergent against a variety of stains. There’s no industry-wide standard for the types of stains that detergents should be tested on, but we largely followed the ASTM International (a global standards development organization) guidelines, which suggest what stains to use, how to make them, and how long to let them set in. They also specify what temperature and wash cycle to use and how to grade how each detergent performed, among other considerations.

In our 2017 testing, we used pre-stained fabrics and simulated a hot-water wash using a stand mixer for the first round, and we followed that with a second round of stain testing using a cold wash in a washing machine with an 8-pound load of towels.

As a starting point for the 2020 update, we purchased the same stain strips we used for washing machine testing (made according to the Association of Home Appliance Manufacturers’s standards). The woven cotton strips come pre-stained with sebum (waxy body oil), carbon black (a mixture of soot and mineral oil), cocoa (chocolate and milk), pig’s blood, and red wine. The human body constantly excretes sweat, skin cells, and sebum, making these the most common types of soil on clothing. Blood and cocoa stains are similar because they are both a mix of proteins, cellular matter, sugar, and fat, making them especially complex to remove. Red wine is a good representation of a tannin stain, similar to ones caused by coffee, tea, or beer. According to Procter & Gamble scientific communications manager Mary Johnson, those beverages all “contain colored ingredients that can be very similar to the dyes in your clothes and therefore leave colored stains behind if not thoroughly removed.”

There are, of course, many more kinds of stains, so to get a fuller picture of how each detergent performed, we stained swatches of white cotton jersey with beef drippings and browned butter (both grease stains), foundation makeup (a non-food grease stain), spaghetti sauce (a tomato and grease stain), mud (which becomes embedded between fibers), and grass (stains from chlorophyll are difficult to remove). Between the strips and our homemade swatches, most of the stains were the same as those we used in 2017, although we previously used lipstick instead of foundation, and the stain strip added carbon (though we ultimately didn’t count the results for that stain—more on that below).

For each detergent, we washed one stain strip and one of our own swatches with a 12-pound load (considered “large” by the detergent and washing-machine industries) made up of garments of various materials and fabric weights. (There was one exception: We were unable to test Tide Heavy Duty on our homemade swatch before the coronavirus pandemic closed our New York City office.) We washed every load in the same machine (our current pick, the LG WM3900H, an HE front-loader), using the normal cold setting and following the dosing instructions for large or heavily soiled loads on each detergent bottle (which ranged from about three tablespoons to about six tablespoons). Because tumble-drying can alter the appearance of stains, we air-dried the stain strips and swatches.

In 2017, we used a spectrophotometer to grade the stains, but this time, we opted for a colorimeter, to measure the color intensity of each stain before washing and after drying. (Colorimeters and spectrophotometers are similar, but the former more closely mimic how we see color and, based on what we’ve seen, are more widely used by the industry for stain testing.) We plugged those numbers into the Stain Removal Index (SRI) equation, which calculates how much of a stain was removed. (It’s used in many industries—not just for measuring stains, but also, for example, for color matching paints or plastics.) We compared the SRI of each washed swatch and strip with the others, and with the control swatch and strip, which were washed on cold with just water, no detergent. The detergents that worked the best on the greatest number of stains became our picks.

Although most of the stains we included in our testing showed us how widely the detergents ranged in effectiveness, a few told us some other things. All of the detergents were able to remove most of the mud and spaghetti sauce, and the stains that remained were virtually indistinguishable. On the other hand, all of the detergents struggled with foundation, so it may be better to pretreat makeup stains instead of hoping they’ll come out in the wash.

Carbon—actually a combination of carbon black and mineral oil—was a particularly tricky stain. A P&G representative told us that the test results for this could be deceptive, since the carbon and oil are not bound together, and a detergent might remove all the carbon and no oil or all the oil and no carbon. Either way, it’s not clear how the detergent performed because we couldn’t decipher the carbon stain from the oil stain. The International Association for Soaps, Detergents, and Maintenance Products, a trade group, also recommends (PDF) removing carbon stains from analysis. We also did not find the grass stains useful, since they weren’t uniformly applied and were therefore difficult to measure. For future testing, we plan to use either a standard pre-stained swatch for grass or to find a more consistent way to make the stain ourselves.

We wanted to test the detergents for odor removal, as we did in 2017, by using them to wash swatches that had bacon grease and then having a panel sniff the laundered swatches for any residual smells. But we were unable to complete testing before the coronavirus pandemic shut down our offices. Our preliminary findings were consistent with the 2017 results, but we plan to redo this test when we update this guide.

This liquid laundry detergent was a top performer in our stain testing, lifting more of a wider variety of stains than any other detergent we tried.

Tide Ultra Stain Release was a better overall cleaner than any other detergent we tested. Although some detergents removed more of certain stains, Tide Ultra Stain Release removed more from a greater number of stains than any of the others. Only Persil ProClean Stain Fighter, our runner-up pick, performed as consistently on so many stains.

This particular variety of Tide is, at 25¢ per medium load (about 6 pounds), one of the most expensive detergents we considered.

Surfactant expert Brian Grady (who was a project engineer at Procter & Gamble, parent company of Tide, from 1987 to 1989) explained to us that detergent prices largely reflect the number of different enzymes in their formulas. And Tide Ultra Stain Release has the greatest number of enzymes of any detergent that P&G makes, a company representative told us. (Ingredients aren’t printed on the bottle, but P&G lists them online.) In our testing, those extra enzymes produced visibly better results, which were also borne out by the colorimeter measurements. Tide Ultra Stain Release bested the competition on most of the stain strip, removing the most sebum, cocoa, and blood, and it was second best at removing the wine (after Persil). (It also performed better than any other detergent on carbon, but we didn’t count the results from that stain in making our pick because we don’t think it’s as meaningful as the others.) No single detergent came out on top for all of our homemade stains. But, like our other picks, Tide Ultra Stain Release did a respectable job on most of them. Tide Ultra Stain Release was also rated Best for Most Tough Stains by Consumer Reports.

Tide Ultra Stain Release is available in HE and standard formulas, is safe for whites and colors, and can be used in all temperatures.

In our previous round of testing, we found that Tide Ultra Stain Release did a pretty good job of removing smells. We wanted to confirm those findings for this update but were unable to do so before the coronavirus pandemic shut down our office. We plan to tackle odor testing for a future update.

We don’t know how this detergent affects clothing over time. We may do another test later in the year.

Tide is made by Procter & Gamble, which also owns laundry brands like Gain, Cheer, Dreft, Era, Bounce, and Downy. That doesn’t mean that other brands, or even other formulas of Tide, will perform the same, though. Some P&G detergents contain four to five different enzymes, while some have none—and, as we found in our testing, you’ll see the difference reflected in their cleaning power.

Tide Ultra Stain Release is less widely available than some of our other picks. If you buy it from Amazon, you might want to avoid purchasing it from third-party sellers, who often sell the detergent at a significant markup. And make sure it’s the right type for your washing machine, since it comes in both HE and standard formulas. Also be aware that it might not come with the scrubber pre-treatment cap that is sometimes pictured.

Although Tide Ultra Stain Release removed more stains than other detergents, it wasn’t able to remove a noticeable amount of the foundation makeup stain we used.

Persil was one of the most effective stain removers in our testing, and it even bested our main pick on several stains. But its strong, lingering fragrance is not for everyone.

Persil ProClean Stain Fighter came in a very close second overall to Tide Ultra Stain Release in our stain testing—so close that we think most people wouldn’t be able to tell the difference between them, performance-wise. Persil also usually costs somewhat less than our top pick, about 21¢ per load, compared with 25¢. Although Persil was in contention to be our top pick, its strong scent, a selling point for some people, is polarizing enough to keep it from beating out the more conventionally scented Tide Ultra Stain Release. (Be sure to give the Persil a whiff before buying, if you have even slight fragrance preferences.)

Persil performed consistently well across the stains on the stain strip. It was second to Tide Ultra Stain Release in removing blood, sebum, and cocoa, and it lifted the most wine. On our homemade stains, Persil removed more of the browned-butter stain than all the other contenders, including Tide Ultra Stain Release. It also got out more foundation makeup than Tide Ultra Stain Release, though Kirkland Signature Ultra Clean, our budget pick, performed the best overall on foundation makeup. Consumer Reports also found that Persil ProClean Stain Fighter worked better for pre-treating stains than most standalone pre-treat stain-remover products.

We were unable to complete odor testing before the coronavirus pandemic closed our office, but based on the numerous reviews we’ve read, we know that Persil’s strong, lingering fragrance is one of its distinguishing features. Many Amazon and Walmart reviewers love the smell, but those who don’t find it “overwhelming” or “overpowering” and are especially bothered by how long the smell persists (even after washing items with other detergents). Numerous reviews mention that the smell fills the whole house (and sometimes even beyond)—which is a plus for some and a dealbreaker for others. Some say that the fragrance made them cough, sneeze, or tear up.

One thing we don’t like about all of the Persil detergents is the opaque red cap, which makes it difficult to judge how much detergent you’re measuring out. Even when we shined a flashlight on the embossed measurement lines inside the cap, they were hard to make out. The cap might be annoying or difficult to use in a dimly lit laundromat or laundry room.

Persil detergents are made by Henkel, a German company that also owns All, Purex, Sun, and Snuggle, among other brands. Persil has been used in Europe for more than a century, but it was only introduced to the US in 2015. Persil ProClean Stain Fighter also comes in premeasured single-use discs. According to a Henkel spokesperson, "unit dose products and liquid detergents are formulated differently as their dose and delivery system is very different." The representative told us that both versions of the Stain Fighter detergent are the most effective in the company’s lineup at cleaning, but we have not yet tested the discs.

This detergent, sold under Costco’s house brand, was better at removing stains than many more-expensive detergents, and it is also good at getting rid of odors.

Costco brand Kirkland Signature Ultra Clean outperformed plenty of more-expensive detergents, even beating out Tide Ultra Stain Release, our top pick, and Persil ProClean Stain Fighter, our runner-up, at removing two of our homemade stains. At 13¢ per medium load, the Kirkland detergent costs about half as much as Tide Ultra Stain Release and about a third less than Persil ProClean Stain Fighter, and it cleans almost as well as they do across a wide variety of stains.

Kirkland’s detergent impressed us with its cleaning performance in testing, ranking among the top five for all but the carbon stain—and it ranked third for blood. The Kirkland Signature also removed noticeably more foundation makeup—one of the most stubborn stains—than any other detergent we tested. Granted, none of the detergents were able to fully remove the large amount we globbed on.

Other publications that have tested Kirkland Signature Ultra Clean have rated it highly, too: Consumer Reports named it Best Value, even though it struggled to clean blood and grass stains in its tests (it did fine on blood for us in 2017 and 2020 testing). Good Housekeeping named it Best Store Brand.

We’ve seen some complaints about the detergent dispenser dripping or leaking. Senior editor Marguerite Preston ran into this problem, and she suggests tilting the container back up immediately after dispensing detergent.

Kirkland Signature also comes in a Free & Clear formulation and in Pacs, but both differ somewhat from the regular version. We plan to test these for a future update. You can find the ingredients of Kirkland Signature Ultra Clean and Costco’s other detergents online.

This dye- and scent-free detergent is one of the most effective stain and odor removers we’ve tested.

If you want a detergent that’s scent- and/or dye-free, or if you have sensitive skin, you might prefer Tide Ultra Stain Release Free. It did so well in our previous stain and odor testing that it won the top spot. We weren’t able to test many scent- and dye-free detergents for this update before the coronavirus pandemic closed our office, but we confirmed with Procter & Gamble that the regular Tide Ultra Stain Release formula “contains a broader variety of cleaning ingredients” than the Free version. We think it’s safe to say then that the regular formula is better overall at removing more kinds of stains, but we’ll follow up with additional testing to confirm this the next time we update this guide. The company’s scientific communications manager, Mary Johnson, also told us that the two detergents have different suds-controlling and hard-water washing ingredients.

Although most people will be fine with regular detergent, Tide Ultra Stain Release Free is a good option for people who have sensitive skin. Dr. Cory Dunnick, the dermatologist we spoke with, said, “If you’re worried about skin irritation from laundry detergent, choose a fragrance-free detergent.” And Tide Ultra Stain Release Free doesn’t contain the preservative methylisothiazolinone, which can cause skin irritation for some people, so this Free version should work if that one bugs you. You can read the full list of ingredients in the formula here.

Right now, you can get Tide Ultra Stain Release Free Liquid only from Target.

All Stainlifter is a budget detergent made by Henkel (the same company that makes Persil). It performed worse than water on three stains (wine, carbon, and sebum) out of the five on the stain strip, and just barely better than water on the other two stains, cocoa and blood.

Gain Original is known for its variety of fragrances and the lingering scent it leaves on laundry. It didn’t do great in our stain tests compared with the more-expensive detergents, but it did leave a strong scent behind. For tough stains, you may need to pre-treat. It’s also available in eco-box packaging.

The plant-based Method Laundry Detergent performed the worst in our tests overall when it came to wine removal—worse, even, than water. It also performed near the bottom on blood and sebum, and slightly below average on cocoa.

Seventh Generation Free & Clear removed stains better than the other plant-based detergents that we tested, but it didn’t do as well as its petroleum-based competitors and especially our picks. It did especially poorly on sebum, cleaning about as well as water. Seventh Generation Free & Clear also comes in a cardboard-packaged version.

Amazon house-brand Solimo performed about average on wine and blood, but it performed worse on sebum and cocoa. It did a noticeably poor job on meat drippings.

Tide Heavy Duty, advertised as a “detergent for mechanics and other pros” for “caked-on dirt, tough odors, and set-in stains,” was good at getting out blood and carbon stains, but not better than the Tide Ultra.

Tide Original came in third in our tests, after our main pick and runner-up, on wine, cocoa, and sebum, and it was about average on blood. Reviewed.com named Tide Original as Best Value because of its good score in its stain tests, too. It’s available in eco-box packaging.

Interestingly, there’s no oxidizing agent or bleach in Tide Plus Bleach Alternative, though it does contain an optical brightener. It did not perform as well as our picks.

Tide Plus Febreze Odor Defense is meant to remove odors, and it also masks them with fragrance, though some Amazon reviewers find the scent too strong. We didn’t test for odor removal, but in our stain-removal tests, this particular formula of Tide didn’t perform as well as our picks on most stains, though it was above average.

Tide Simply Clean & Fresh, marketed as a budget Tide, was one of the worst performers in our stain-removal tests, and somehow it did worse than water on cocoa. The formula does not contain any enzymes, which are the most important stain-busting ingredients found in most laundry detergents. It’s poorly rated by Amazon reviewers, with a disconcerting number complaining about allergic reactions they believe were caused by this Tide.

We plan on reviewing Arm & Hammer, Tide Purclean, and Gain Botanicals in the future, along with pods.

There’s a surprising amount of science packed into that bottle of laundry detergent. Most detergents contain some or all of the following ingredients: surfactants to remove dirt and grease, enzymes for stain removal, oxidizing agents for bleaching, polymers for all kinds of reasons, optical brighteners to make white fabrics look whiter, water softeners to make sure the surfactants work well, anti-foaming agents to make sure your laundry-room floor stays suds-free, and more. The ingredients aren’t usually printed on the detergent bottle, but if you’re curious, you should be able to find them listed on the company’s website. (For Tide and Persil products, as well as some others, look for a link to the SmartLabel, which lists the ingredients and describes what they’re used for.)

Among the most important ingredients in a laundry detergent are the surface active agents, or surfactants. These molecules work like soap, pulling soils off surfaces and making them easy to wash away (and, unlike soap, they don’t make soap scum). Some surfactants you might find in laundry detergent are alcohol ethoxy sulfate, various laureths (such as laureth-6, -7 or -9), alkyl sulfate, sodium lauryl sulfate, ethoxylated lauryl alcohol, the list goes on.

Another crucial ingredient: enzymes, large biological molecules that speed up chemical reactions, including those that break down molecules—stains, in the case of laundry detergents. Enzymes are specific, meaning they each usually target one kind of molecule, so you need a wide variety of enzymes to tackle a wide variety of stains. Brian Grady, director of the Institute for Applied Surfactant Research at the University of Oklahoma, emphasized the importance of enzymes in detergents when we spoke with him. “Enzymes are one of the big price differentiators between detergents. A less expensive detergent is going to have a harder time cleaning certain stains and may not clean them at all,” he said. This is because cheaper detergents usually have fewer types of enzymes.

Because enzymes are catalytic, they work without getting used up, so the small amount you add to a load of laundry will keep breaking down its specific target until you either run out of water or the target itself breaks down.

There are all kinds of enzymes in laundry detergent. If you see an ingredient in a laundry detergent that ends in “-ase,” it’s most likely an enzyme. Some of the most common ones: amylase, which is found in our mouths and breaks down starches; lipases, which break down grease; and proteases, which break down protein (like blood or gravy). Cellulase works on the fabric (specifically cotton) instead of the stains. It’s designed to do things like prevent pilling and restore colors.

Oxidizing agents, which include hydrogen peroxide and sodium percarbonate (one of the main ingredients in OxiClean), break up certain molecules that appear colored (not just the particles that make up stains, but also those in dyes), producing smaller pieces that are no longer visible to the human eye. These ingredients are often found in detergents that say they include color-safe bleach or a bleach alternative (but not always: Tide with Bleach Alternative contains only optical brighteners). You won’t find chlorine bleach in laundry detergent because it deactivates the enzymes—the main stain-busting ingredients—found in the detergent.

Hard water contains a lot of dissolved minerals, such as calcium and magnesium, which can affect the performance of surfactants, so companies add water softeners (which might come in the form of things like builders or sequestering agents) to make sure that detergents work the way they should.

A lot of things can be called polymers; this is simply the term for strings of molecules that are made up of a smaller repeating unit. One common use for polymers in laundry detergent is as a dispersion agent, or an anti-redeposition agent. When detergent lifts dirt off your clothes, the dirt is mixed with surfactant in the wash water but will resettle all over your clothes, making them look dingy and gray. An anti-redeposition polymer keeps the soil dispersed in the water so it’ll go down the drain instead of back onto your shirt.

Optical brighteners are compounds that stick to the surface of your clothes and glow when UV light hits them. Since sunshine has UV light in it, we see this glowing light as white—hence, clothes look whiter. (To clean their uniforms, servicepeople are not supposed to use laundry detergent that has optical brighteners, because it makes uniforms easier to see in low light and with night-vision equipment.)

The last ingredient of note is some kind of suds suppressor, also known as an anti-foam agent, which, true to its name, prevents excess foaming.

1,4-dioxane is a contaminant, not an ingredient, and it’s a potential human carcinogen. It’s a byproduct of making ethoxylated ingredients, such as sodium laureth sulfate (or sodium lauryl ether sulfate, or SLES, a common detergent surfactant) or polyethylene glycol (better known as PEG compounds). It’s been classified by the EPA as a probable carcinogen, which means that it has caused cancer in animal tests, but there haven’t been any conclusive human tests.

In 2011, the group Women’s Voices for the Earth commissioned lab tests that found elevated levels of 1,4-dioxane in both Tide Liquid Original and Tide Free & Gentle liquid laundry detergents. The levels fell within the amounts allowed by federal guidelines, but advocacy groups have continued to commission lab testing, and to push for companies to remove the ingredient from their products and for increased regulation of the substance. In 2019, the group Citizens Campaign for the Environment tested shampoos, body washes, baby products, laundry detergents, and soaps for 1,4-dioxane, and published its findings (PDF).

In December 2019, New York Governor Andrew Cuomo signed a bill that would “prohibit the sale of cosmetic or cleaning products containing 1,4-dioxane.” The bill came as a result of contaminated drinking water (1,4-dioxane) in Long Island. It will be enacted by the end of 2022, banning sales of products with trace concentrations of 2 ppm or higher, and, by the end of 2023, 1 ppm or higher. For reference, according to the Citizens Campaign test results, detergents from brands like Tide, Gain, Persil, All, and Arm & Hammer all have 1,4-dioxane levels above the limit. Although the detergent companies aren’t actively putting this contaminant into their detergents, it’s unfortunately a byproduct of their formulation process. Surfactant expert Brian Grady told us, “You’re going to see significant changes in [the detergent space] because, to my knowledge, almost all of the detergents on the market today won’t pass the [new] standards.” He mentioned a few possible consequences of the new bill. “There are processes out there that can remove 1,4-dioxane, at a high cost, so the cost of detergent will go up. [The detergent companies] could try to reformulate, to get below the standard, which will also raise the cost. Or some type of innovation would occur involving reducing or replacing SLES, the ingredient that causes the dioxane byproduct.”

According to the Nassau Suffolk Water Commissioners’ Association, 1,4-dioxane has reached groundwater (which Long Island relies on for its drinking supply) primarily because of industrial manufacturing operations on Long Island. But trace amounts present in household products (like detergents) also get washed down the drain and seep into the ground, eventually entering Long Island’s aquifer. Trade groups like the American Cleaning Institute expressed disappointment when the legislation was signed, claiming that the bill would have “no measurable impact on groundwater.” ACI argues that the high levels of 1,4-dioxane in the Long Island drinking water are not comparable to the relatively small amount in cleaning products.

We asked Procter & Gamble, the company that makes Tide, how it was going to address the new restrictions. The company responded: “With respect to the impact of 1,4-dioxane legislation on the laundry industry, you can reach out to the American Cleaning Institute.”

Phthalates are plasticizers, which soften up hard plastics and make them harder to break. These types of chemicals are in a lot of products, but how exactly they affect our health is not clear. Some tests using lab animals show that they can harm reproductive systems, and there’s some evidence that the compounds can affect human fertility as well. The Centers for Disease Control and Prevention has found either phthalates or its metabolites in most people it has tested. The FDA said that phthalates don’t pose a risk to our health the way they’re used in detergents at present, but it is watching the situation.

Phthalates may be found in the fragrance mixture of laundry detergents, although they may not be listed among the ingredients, since companies are not required to say what’s in their fragrances (though some do). If you’re worried about this ingredient, choose fragrance-free detergents. In addition, some detergents don’t use phthalates in their fragrances and will say so on the label.

Methylisothiazolinone is sometimes used along with methylchloroisothiazolinone. They’re known as MI and MCI, respectively, and are used as preservatives in a lot of cleaning and beauty products. Preservatives are an important ingredient, because they prevent the growth of mold and bacteria, which can make us sick. But either by itself or in conjunction with MCI, MI can cause allergies or irritation, and it’s more likely to be in liquid laundry detergents than in powdered ones.

There’s also some data out there that MI may be a neurotoxin. A few studies show that putting it directly on rat brain cells kills neurons, and other studies (PDF) indicate that feeding it to test animals or putting it on their skin in high doses—much higher than is allowed in rinse-off cosmetics and products with surfactants—leads to a wide range of negative effects, from ataxia to diarrhea. In 2016 the EU banned MI from leave-on products (like lotions), and reduced the maximum concentration allowed in rinse-off products from 0.01 to 0.0015%. In the US, the Cosmetic Ingredient Review expert panel—funded by an industry trade association but with an independent review process (PDF)—reviewed the most recently available data and concluded (PDF) that MI was acceptable in concentrations up to 7.5 ppm for leave-on products and 15 ppm for rinse-off ones.

If you want to avoid preservatives, read labels (usually only listed online). But for most people, MI/MCI is unlikely to cause skin irritation, especially since laundry detergent doesn’t usually come in contact with our skin (if you’re using the correct amount, it should rinse out of your clothes in the wash), unless you’re using it for handwashing or you spill some on yourself.

Optical brighteners, as mentioned above, are molecules that companies add to laundry detergent to make your clothes look whiter and brighter. There are concerns that optical brighteners are a health hazard, an environmental hazard, or both. In the past, the EPA studied several of these compounds (PDF) and concluded that they are unlikely to build up and persist in the air and soil. However, that link is an archived link, and the information is not available on the EPA website anymore.

Nonylphenol and nonylphenol ethoxylates are related compounds. Nonylphenol ethoxylate is made from nonylphenol. They’re usually listed as a pair because nonylphenol ethoxylate will break down into nonylphenol in soil and water, and although they’re both nasty, nonylphenol is the nastier of the two. They’re both endocrine disruptors, and they tend to accumulate in the environment, where they can harm wildlife. If you’re worried about nonylphenol and nonylphenol ethoxylates, look for detergents with the EPA Safer Choice label; they’re free of both.

Detergent companies don’t put phosphates in laundry detergent anymore, and they haven’t in the US since the early 1990s. Phosphate-based surfactants make great cleaning agents, but they also make algal blooms, which pollute lakes and streams. So the EPA said no more over 20 years ago. Procter & Gamble used to use phosphates in its detergent, but it removed them from all formulas in the US in 1995 and worldwide in 2015.

High-efficiency washing machines (which include all front-loading machines and some top-loading washers) use only 20% to 66% of the water and 20% to 50% of the energy used by traditional agitator models, according to the American Cleaning Institute’s HE Washers and Detergents guide (PDF). This is because in HE washers, the clothes don’t sit in a tub of water. Instead, they’re wetted at the beginning and stay saturated throughout the wash—the washer adds more water if it detects that the clothes are too dry. HE machines are also gentler on fabrics because they don’t have agitators.

You can use an HE detergent in a regular washer, but you can’t use a regular detergent in an HE washer.

Because HE washers use less water, you need a special detergent to use in them. “HE detergents are formulated to work with much less water,” surfactant expert Brian Grady told us. “Most importantly, they foam less and are at a dosing amount/concentration to work with less water.” According to Grady, HE detergents also often have special ingredients (usually charged polymers) that help keep soils suspended in the small amount of water found in HE machines, so they don’t re-deposit onto your clothes.

If you use the suggested amount of regular detergent in an HE washer, the small amount of water in the HE machine will have a tough time dissolving all the bubbles caused by the regular detergent. HE machines are smart and will run longer to rinse away the excess suds, but some detergent residue may stick to your clothes regardless and can also build up in your washer over time. If you try to use a smaller amount of regular detergent in an HE machine to keep the suds down, you may not end up with enough to get your clothes clean.

The bottom line is that you can use an HE detergent in a regular washer, but you can’t use a regular detergent in an HE washer. So if you own a front-loading washer, be sure to buy HE detergent (all front-loaders are HE). If you own a top-loader, check to see whether or not it’s HE.

Laundry pods are pretty convenient—toss a pod in the washer, throw your laundry in, turn the machine on. However, if you share a house with children or people with dementia, you might want to rethink jumping on the pod bandwagon, since ingesting a laundry pod can make someone seriously sick and can even be lethal. Pod poisonings (PDF) have put kids in the hospital—and sometimes in the ICU. According to Consumer Reports, eight people died as a result of biting into the pods between 2012 and 2017. Two of those people were kids, and the other six were adults who had dementia.

Pods make up a small portion of the market share (20% according to a recent Nielsen report, and less in previous years). Yet, according to the CDC (PDF), almost half of the laundry-detergent poisonings reported to the National Poison Data System during one month in 2012 were from pods. So why the disproportionate number of pod exposures? Many brands make multicolored pods that look bright and attractive, and as the CDC has noted, “Children might be attracted to pods because their colorful appearance and size are similar to candy.” This problem has gotten so dangerous that Consumer Reports is not recommending pods at all anymore.

But companies have taken various steps to try to increase the safety of their packaging. Procter & Gamble added a lid to the Tide Pod container—similar to that of a child-proof medicine bottle—that you have to squeeze and twist to open. Persil uses another type of child-resistant closure, and other brands use bags that are difficult to unseal.

Also, many companies have added bittering agents to the outside of their pods; these make someone spit the thing out within a few seconds.

Keep in mind that the potential safety hazards of pods don’t mean they aren’t a good laundry choice for some people. If you have to take your laundry to the laundromat or carry it down to the basement laundry room of a multistory apartment building, pods are convenient. However, they did not do as well as powders or liquids in our 2017 tests, and they have been known to stain clothing when not dissolved properly. They can also get stuck in the gasket of a washing machine—especially commercial ones at laundromats—and then fail to dissolve in the wash. We also have doubts about the effectiveness of using unit-dose detergents like these (or sheets or tablets), since we think most people are unlikely to weigh out their loads each time they do the wash.

Laundry detergent allergies are rare, according to board-certified dermatologist Cory Dunnick, who is director of the Dermatitis and Contact Allergy Clinic at the University of Colorado. “I think there’s been a lot of marketing by laundry detergent companies to distinguish their brand as better for babies or sensitive skin. Thus, consumers have come to believe that laundry detergent can be a potential cause of skin rashes and allergies. But in general, that is not the case.”

Dunnick says it’s more likely you’re irritated by something you’re putting directly on your skin, like body wash, moisturizer, or topical antibiotics. “Liquid detergents contain fragrance, preservatives, and surfactant ingredients which can cause contact allergy. However, detergents go through a rinse cycle in the washing machine, and very little of these allergens are retained in fabrics to cause an allergic reaction,” she told us. If you do have a reaction to an ingredient like methylisothiazolinone (MI)—a common preservative in detergent as well as in shampoo, conditioners, and body washes—it’s more likely to be from those products that you apply directly to your skin.

Dunnick notes that irritation could also be caused by other things on your clothing. “You could be allergic to textile dyes or fabric finishes that have formaldehyde that make them wrinkle-resistant, or patients could be allergic to rubber accelerators in some clothing, but it’s generally not the laundry detergent itself.”

All that said, if you think you’re having a reaction to laundry detergent, make sure you’re not using too much, try double-rinsing your laundry, and avoid direct contact with the detergent. Or try a dye- and fragrance-free detergent like Tide Ultra Stain Release Free, which is also free of the preservative MI. Just keep in mind that, as Dunnick told us, there’s no industry standard definition of “hypoallergenic.” “[That word] is not saying certain ingredients are included or excluded.”

Terms like “non-toxic,” “eco-friendly,” “green,” or “natural” can be confusing. As Katie Jennings, a formulation scientist at Seventh Generation, told us, “None of those terms have definitions in the industry.” Jennifer Ahoni, scientific communications manager at Procter & Gamble, agreed: “There are a lot of different words that are not clearly defined. There’s not necessarily an industry recommendation on what exactly ‘natural’ means.”

Detergents marketed as eco-friendly tend to use more plant-derived, rather than petroleum-derived, ingredients (even though it’s difficult to say whether plant-derived ingredients are always better for the environment). And they may avoid some ingredients of concern, like optical brighteners, SLS or SLES (the surfactant that causes the 1,4-dioxane byproduct), and phthalates. You’ll have to read the label to understand what being green entails for a certain brand.

Even then, not all labels are equally clear. You can get a sense of how they might be misleading by browsing the Federal Trade Commission’s Green Guides, which provide guidance on how companies can present green claims in a way that’s transparent and factual. These guidelines are not requirements, but there are a couple of independent certifications you can look for on the label if you’re interested in buying a more-sustainable detergent or in avoiding possibly harmful ingredients.

If you’re concerned about sustainability, the USDA BioPreferred Program certifies that a product contains a certain amount of “biobased” ingredients “derived from plants and other renewable agricultural, marine, and forestry materials.” To get the USDA Certified Biobased Product label, a detergent has to contain a minimum of 34% biobased ingredients, as confirmed by a third-party lab test. The label tells you exactly what percentage of the formula is made up of biobased ingredients. For example, the label on Seventh Generation’s Free & Clear detergent tells you that it’s 97% biobased. We asked the company what the other 3% was, and it told us, “The 3% in our formulation is our preservatives… We spend an enormous amount of time in this building trying to find a plant-based preservative, but at this time our preservative is petroleum-based.”

You’ll have to read the label to understand what being green entails for a certain brand.

If you’re concerned about ingredients that are potentially harmful (either to people or to the environment), you can also find detergents that are certified by the Environmental Protection Agency’s Safer Choice Program. To obtain the Safer Choice label, a product must meet specific human and environmental safety criteria—the EPA examines a product’s entire formulation for things that may be acutely or chronically toxic. Unlike the USDA BioPreferred Program, the Safer Choice Program takes into account performance as well as chemical ingredients, packaging, ingredient disclosures, and volatile organic compounds. That means detergents with the Safer Choice label meet requirements set in the Consumer Specialty Products Association Guidelines for Anti-Redeposition Properties of Laundry Products (a test method to make sure detergents are actually removing the dirt from your clothes) or an equivalent method agreed upon by the Safer Choice Program.

If you want to make sure the product you’re using wasn’t tested on animals, look for the Leaping Bunny certification, which indicates there has been no animal testing at any stage in development of the product or formulation.

Seeking out these certifications on the label is your best bet if you’re looking for a more sustainable or environmentally friendly detergent. But the American Cleaning Institute also has some simple tips on how to be a little more sustainable when you do your laundry: Use the recommended amount of detergent, use products until they are finished, recycle the containers, wash full loads, and hang-dry your clothes (dryers use a lot of energy).

For baby items and cloth diapers, don’t bother with a baby-specific laundry detergent. They are expensive and unnecessary.

For cloth diapers, you just need a detergent that doesn’t have anything in it that will stick to the fabric. Anything left behind on the surface of the diapers is going to interfere with how absorbent they are, which in turn could cause leaks. Fabric softener, optical brighteners, and fragrance are three things you want to avoid, since those are designed to stick around. Among the detergents we tested, Seventh Generation Free & Clear is one of the few that don’t have any of these. All of our picks have optical brighteners.

According to the American Academy of Pediatrics, many parents wash their babies’ clothes with the rest of the family’s laundry without encountering any problems. You would need a detergent formulated for sensitive skin only if your baby developed any skin irritation.

If you’ve heard you should avoid petroleum-based detergents because they also stick to diapers, don’t believe it. A surfactant that comes from oil is no different than the same surfactant that comes from plants; they have the same molecular structure, but those derived from plants just cost more. You will have surfactants sticking to diapers only if you use too much detergent or you don’t rinse well enough.

If you have concerns about the cost and/or the possible toxicity of laundry detergent, you may have considered making your own. Although popular detergent recipes are easy and relatively cheap to make, they don’t clean as well as the store-bought kind and can leave your clothes and washing machine in bad shape.

Every detergent expert we talked to advises against making your own detergent because of how much science and expertise goes into an effective cleaner. DIY formulas usually have only three ingredients—some kind of soap, washing soda, and borax. They don’t have enzymes, which target and remove specific types of stains; surfactants, which work better at cleaning than soap and don’t leave behind soap scum; or polymers, which keep dirt from redepositing on your clothes and making them turn gray over time.

Homemade detergent can also damage your clothes. The soap can react with minerals in hard water to leave behind soap scum. And with soft water, it’s easy to use too much soap; this can also result in residue left on clothes, which can cause colors to fade and increase the wear on fabric. Soap scum can cause problems in washing machines, too, leading to bacteria and mold growth, which can then get on your clothing.

We are currently testing more than 25 laundry detergents. Several of the formulas are free of dyes and synthetic fragrances, including Seventh Generation Liquid Laundry Detergent, Dirty Labs Bio Enzyme Laundry Detergent Free & Clear, Defunkify Liquid Laundry Detergent, and Zum Laundry Soap.

Mary Johnson and Jennifer Ahoni, scientific communications managers, Procter & Gamble, Cincinnati, in-person interview, February 26, 2020

Sol Escobar, senior engineer, Procter & Gamble, Cincinnati, in-person interview, February 26, 2020

Brian Grady, PhD, director of the Institute for Applied Surfactant Research, University of Oklahoma, phone interview, March 3, 2020

Katie Jennings, formulation scientist, Seventh Generation, phone interview, February 21, 2020

ASTM D 4265-14: Standard Guide for Evaluating Stain Removal in Home Laundering (subscription required), American Society for Testing and Materials, 2014

Cory Dunnick, MD, board-certified dermatologist and associate professor and director of the Dermatitis and Contact Allergy Clinic at the University of Colorado, phone interview, May 21, 2020

Jonathan Propper, founder and CEO, Dropps, phone interview, March 20, 2020

Sarah Bogdan

Sarah Bogdan is a former staff writer at Wirecutter covering appliances. Previously, she tested cleaning products and appliances at Good Housekeeping. Her degree in mechanical engineering and product design helps her understand how products work and how people interact with them. When she’s not tackling messes, she’s tackling rivals on the rugby field.

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