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How we test disposable nappies and nappy pants
Principal researcher/writer at Which? delivering award-winning health, baby and safety investigations, including our annual sunscreen tests.
In this article
- Which nappies or nappy pants absorb liquid quickest?
- Which nappies or nappy pants lock in wetness away from my baby’s skin?
- Which nappies or nappy pants won't leak?
- Which nappies or nappy pants do parents rate?
- How we calculate the scores
- How we choose the products
- Is it a Best Buy? What our verdicts mean
- Our nappies and nappy pants experts
Our independent reviews combine results from expert lab tests with unique insights from parents to reveal the best disposable nappies and nappy pants for your baby.
Nappies are constantly being reformulated and updated by manufacturers. A nappy tested in 2025 may not be the same product that's on the shelf in 2026. That's why it's important that we keep testing them rigorously in our labs so you know which products will keep your baby dry and comfortable.
We're funded by Which? members and buy everything ourselves. We don't accept free samples and pay for our own testing. This prevents manufacturers from influencing our reviews and ensures we test what parents are picking up off the shelf.
Find the best disposable nappies and nappy pants.
We’re not influenced by third parties, and we don't accept freebies from product manufacturers or retailers. As a not-for-profit organisation, we have no owners, shareholders or government departments to answer to, so we work entirely on behalf of you, the consumer – nobody else.
Read our full statement of editorial independence.
Which nappies or nappy pants absorb liquid quickest?
A nappy that soaks up liquid quickly can help reduce the number of nappy accidents you'll need to deal with.
We apply synthetic urine to the nappy and time how long it takes to fully absorb the fluid. We repeat this four times to measure the rate of absorption as the nappy fills up, which is designed to reflect a nappy being worn overnight.
What separates a good result from a poor one?
A good nappy should be able to absorb wetness quickly, regardless of whether it's the first or the fourth time they wee.
Which nappies or nappy pants lock in wetness away from my baby’s skin?
To check if the nappy can keep liquid locked away inside its core, we place filter paper on top of a fully fluid-loaded nappy and weigh it down. We measure the amount of liquid absorbed by the filter paper to work out how well the nappy holds in fluid.
This is designed to replicate your baby sitting on top of a nappy that they've been wearing for a while.
What separates a good result from a poor one?
Some babies, especially those with delicate skin, can develop nappy rash if they're left in a nappy that lets wetness back onto the skin. The best nappies don't let this happen.
Which nappies or nappy pants won't leak?
Even if a nappy can soak up a lot of liquid, if it lets wetness leak through to the outside, you could end up with soggy babygrows and damp bedsheets.
We apply synthetic urine to the nappy four times, recording the amount of liquid, if any, that leaks out of the nappy each time.
What separates a good result from a poor one?
The best nappies will keep liquid on the main central section of nappy padding. Our lab experts look out for damp patches on the elastic sections of the leg guards to see if it's likely they'll leak.
Which nappies or nappy pants do parents rate?
We use a panel of 30 parents to try out each of the nappies on their babies and get them to give us their thoughts and ratings for them. They cover similar areas to the tests mentioned above, but this time with the benefit of parent and baby experience.
What separates a good result from a poor one?
Parents will provide ratings on daytime absorption, night-time absorption, skin irritation, breathability and how easy they are to use. They'll share their experiences and provide comments on the different nappies, as well as ratings, with the highest-rated nappies scoring best.
How we calculate the scores
The results from each of the tests described above are combined to give an overall percentage score for each disposable nappy or nappy pant we review.
Kamisha Darroux, Which? principal scientific advisor, says:
'We regularly ask Which? members what matters most when choosing which nappy to use on their baby. I then use this information when developing the test programme and evaluating the testing data we receive from the laboratory. Since our members said that absorption and preventing leakages matter most, these elements carry the most weighting when calculating the score.'
Our total test score for nappies and nappy pants is made up of the following factors:
50% performance lab tests
- 15% absorption rate
- 15% protection against leakage
- 15% holding wetness inside
- 5% breathability
50% user trial tests
- 15% day and night absorption
- 7.5% leakage
- 5% breathability
- 5% redness/irritation
- 5% ease of putting on and taking off
- 5% nappy fit
- 2.5% visual aspect
- 5% overall rating
Are reusable nappies worth it? Find out more about the different types and the pros and cons of using them
How we choose the products
Whether it's an expensive eco nappy or an own-brand supermarket nappy, the materials that make up the product are constantly being tweaked or reformulated. This means a product launched one year may not be the same as the one in shops a year later.
Lauren Temple, Which? principal market analyst, says:
'I scour the market to make sure we're testing all widely available nappies and nappy pants. Whether it's an upgrade to a Pampers premium line or an own-brand launch from a discounter, I keep in regular and direct contact with manufacturers and supermarkets to make sure we have coverage of the latest formulations.'
Why don't we test reusable nappies?
We currently don't test reusable nappies. This is because they are a very personal product and what works best for one baby may not work for another.
They can also be worn in different ways. For example, parents can opt for an all-in-one or two-piece and may use them in combination with reusable or disposable inserts to improve absorbency.
Plus, it's a market made up of lots of smaller manufacturers, which makes it difficult to keep ahead of product launches in a meaningful way.
Is it a Best Buy? What our verdicts mean
Best Buys
85% or more
A Best Buy disposable nappy or nappy pant must excel in our tests and score 85% or above. But it's still worth reading our Best Buy reviews to check if there are any factors that might change your mind on particular ones.
Don't Buys
45% or less
Any disposable nappy or nappy pant scoring 45% or less is a Don't Buy. This means the nappy did so poorly in our tests that we don’t recommend you buy it.
Great Value nappies
80% or more
The cost of buying nappies can significantly add up over time, which is why we've also made Great Value recommendations. Nappies must score 80% and, per nappy, be at least 20% cheaper than the average cost of a nappy.
Great Value nappy pants
70% or more
Nappy pants must score 70% or more in our tests and, per nappy pant, be at least 20% cheaper than the average cost of a nappy pant.
Some of our Great Value nappies also score highly enough to be Best Buys. Read our nappy reviews and use the Best Buy and Great Value filters to find the top nappies for your baby.
Our nappies and nappy pants experts
Running our test projects is a group effort, with several members from across the team contributing to each one.
We thoroughly re-evaluate our testing processes every year to ensure they're useful to you, and we ask the Which? community to tell us what matters most when choosing a nappy or nappy pants.
Here's the team that makes it happen:
Principal researcher and writer, Hannah Fox: Hannah turns the enormous amount of data, test results and feedback from our panel of parents and lab experts into in-depth and unbiased product reviews. She's reviewed thousands of baby products, and her experience of writing nappy reviews means she knows exactly how to cut through the marketing jargon to spell out what makes a nappy good or bad.
Baby and child editor, Daniel Davies: Daniel goes over all our nappies content, ensuring that what you're reading is clear, easy to understand, free of confusing jargon, and exactly what you need to know about nappies and nappy pants.
Principal scientific advisor, Kamisha Darroux: Kamisha knows nappies and nappy pants inside and out, and has an in-depth knowledge of what happens when a nappy performs poorly in our testing and how that will impact the total test score. She helps to shape the nappies test programme and is a whizz at converting hundreds of lines of data into the star ratings and scores you see on the reviews.
Principal market analyst, Lauren Temple: Lauren is constantly on the lookout for the latest new launches in the nappies market to ensure we're testing the models that parents want to buy. She regularly liaises with manufacturers and leading supermarkets so that she knows which nappies and nappy pants will be launching and when.