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How we test laundry detergents

The rigorous testing that helps you find the best laundry detergent for your washing machine.

laundry detergent

We've tested hundreds of detergents over the years, and publish new laundry detergent reviews every year because, along with your washing machine, a top performing detergent is the key to clean clothes. Detergent also makes up a third of the running cost of your washing machine. 

Why do we need to test so often? While you may have your favourite detergent that you've been using forever, that brand's current formula probably has no relation to how it was formulated five years ago. Advances in chemical technology mean that you can't rely on your favourite brand to stay the same, because they're always trying to beat the competition - which is why we test so often.

One of the big questions is what kind of stains is your laundry detergent best for? This depends on the stain type and the detergent. Do you work in a surgery, do you have children, regularly spill chocolate ice cream or are you a chef? They'll all call for different types of stains. It's also why we ask you via Voice Your Choice which stains you get most, so you can decide which stains we test against.

Our expert testers

With over 30 years' experience in the laundry lab, we're proud of our expert testers. They've seen all types of laundry detergents come through the labs, but one thing never changes – they need to find what gets your clothes clean. We focus on the basics so that when it's time to buy, you can be sure the laundry detergent you buy will work well.

How do we choose which laundry detergents to test?

Why do we choose one laundry detergent over another? There are a number of reasons for this, but our priority is to test what you'll see in stores. That means that sometimes we might not cover a brand that sells directly, and instead focus on the big brand models that you'll most likely see in the retailer. This will probably include well known detergent brands like Cold Power, Dynamo, Drive and Omo, along with major grocery store brands like Aldi, Coles and Woolworths. That means you can at least see it before you buy it and see if you're happy with it. How do we know what's in retailers? We check current market figures to see what's selling well. We'll also include detergents that you've requested – if a lot of members want it, we'll test it.

Once we know what you want to read about, our buyers use your member fees to buy the laundry detergents anonymously from a variety of retailers, then bring them in as is. This means we get what you'd get, so we can be sure the results are what you'll find rather than potentially 'tweaked'.

How does CHOICE test laundry detergents?

Contrary to popular opinion, we don't get CHOICE employees to bring in their dirty laundry. We use set loads of cotton materials, and attach a variety of pre-stained fabric swatches to them. These stains are made in the Netherlands and include the most common stains as chosen by you, our members. Why do we use pre-stained swatches? Because comparing laundry detergents fairly means you have to use identical conditions for all of them.

The swatches of cloth that are embedded with a specific amount of dirt are identical and made up of a very specific formula. These are used all over the world by large detergent makers, plus other consumer organisations and are considered a standard in testing detergents. Using them minimises the amount of variables so you can see which detergent comes out best when comparing them.

After we put the recommended dose of detergent in either a front loading washing machine or a top loading washing machine (we have four identical washers of each type so there is minimal difference in machine type), we use a cold wash (20C) on a standard wash for our testing.

Once we run the wash, we retrieve the stained swatches and compare how clean they are post wash to how dirty they were pre-wash. We use a spectrophotometer to measure the difference which is a better measure than the human eye.

Stain selection and weighting

This is the list of swatches we use, as chosen by you, our members. They usually change every few years in response to surveys we send to out to members.

  • General detergency (35%)
  • Sebum – natural oils, perspiration (20%)
  • Grass/mud (15%)
  • Olive oil (7%)
  • Makeup (6%)
  • Chocolate ice cream (6%)
  • Baby food (5%)
  • Aged blood (6%)

Why don't we test smell?

There are a variety of reasons for this, but it mostly comes down to subjectiveness. Some detergents are strong sellers in the market, so we assume many people don't care about the smell, or don't think it's strong. There would be other people who do think a smell is overpowering. How do we make an assessment on what's strong and what's OK?

We've contacted professional fragrance makers about this aspect, and really they could only tell us what the fragrance is supposed to be representative of in terms of fragrance type (lemon, orange, etc), not strength of smell. Again, because what they consider strong could be quite different to what someone else considers strong.

This will also depend on how old the detergent is – the newer the box is the more likely it is to be a strong smell, because fragrance fades over time. Many manufacturers aren't too transparent about when something is made, so if we found one was strong, and another was weak (assuming we even could) then it could be based on how old the box is. That kind of assessment wouldn't be fair to the manufacturer or our members.

Your best bet for the moment is to take the smell test in the retailer, assuming you can take the container far enough away from the pungent smell that is the detergents aisle. No, we aren't advocating opening the box in the retailer, but often smell permeates through the cardboard of boxes, and the lids can be opened – as long as they aren't secured with a twist top – of bottles to take a whiff.

Why do some laundry detergents change results year on year?

CHOICE tests within all the variables we can control. We utilise the same stain swatches, washing machines, testers, temperature and humidity, hardness of water, ballast (the load that we attach the stains to) and methodology. We even purchase all the products the same way you will so it's a more realistic result. And yet year on year we will commonly see a brand / model of detergent change.

One thing that CHOICE does not have control over is the formula that each manufacturer utilises for their detergent. We don't know why some manufacturers will adjust their formula throughout the year. We have chatted to industry experts who have said that it might be their supplier contracts changing or trying to improve their results by adjusting their formula. In some cases they may order their formula ingredients through a third party supplier and not even know that the supplier has changed their suppliers.

This is why we test the entire market available in national retailers each year so we can identify these changes in the manufacturer formula. It can be frustrating to see that your brand or detergent type has changed performance results, but it's also why we keep testing - so you know when to switch to the better performing detergent.

Our test lab

We maintain a lab that is up to date with the latest reference machines and calibrated measurement tools for our testers to bring you the right results.

We care about accuracy. See something that's not quite right in this article? Let us know or read more about fact-checking at CHOICE.