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1 October 2020

How we test disposable nappies

Discover the lengths we go to uncover the best nappies for your baby
Baby in nappy on changing table
Rebecca Marcus

Our independent reviews combine results from expert lab tests with unique insights from parent surveys to reveal the best disposable nappies for your baby.

Our test results will tell you which nappies absorb liquid quickly and lock moisture into the core away from your baby's delicate bottom.

Each nappy we test is assessed in the same way and our tests are designed to answer the key questions you have, including:

Find out which disposable nappies you can rely on in our disposable nappy reviews.

Which nappies 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.

A good nappy should be able to absorb wetness quickly, regardless of whether it's the first or the fourth time they go to the toilet.

Which nappies 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 it's been wearing for a while.  

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 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.

Which nappies have a strong fastening?

We measure how much force (in Newtons) is needed to open the Velcro fastening on the nappy. The greater the force needed, the more secure the nappy fastening.

Choosing a nappy with a strong fastening will ensure it stays in place the whole time your baby is wearing it.

Which nappies leave parents most satisfied?

Lab testing is a great way to measure how well a nappy absorbs and retains liquid, but we know that all babies are different, so we haven't just relied on lab testing to work out which nappies are winners.  

In March 2020, we asked 1,242 parents to rate the disposable nappy brands they use. They scored the comfort, fit, ease of use and value for money offered by the nappies and told us how satisfied they were with them.

Read our guide to the best disposable nappy brands to find out how parents rate Pampers and supermarket own-label nappies from the likes of Aldi, Asda, Lidl and Tesco.

Should I buy it? 

The results from each of the tests described above, as well as the results of our survey, are combined to give an overall percentage score for each disposable nappy we review.

Our total test score for nappies is made up of the following factors:

  • 17% absorption rate
  • 17% protection against leakage
  • 17% holding wetness inside
  • 20% customer score
  • 10% comfort
  • 10% fit
  • 10% value for money

A Best Buy disposable nappy needs to score 74% or above, while any disposable nappy 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.

For more advice on choosing disposable nappies, head to our guide on how to buy the best disposable nappies.

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