How we test mattress toppers

Why and how do we test mattress toppers? Find out what happens to them in our specialist lab and what makes our tests the most rigorous. 

Almost all free-to-access websites review mattresses toppers using individual testers and generate scores based on that person's preferences. Free sites also typically get mattress toppers free of charge from manufacturers or their PR representatives. 

We use state-of-the-art equipment in a lab-based scenario. The Which? test score is calculated purely on the measurements and ratings supplied by the lab, meaning there is no room for unconscious bias when giving a rating. We also buy every double mattress topper we test - we don't accept free samples for any of our full lab tests, so you can have complete confidence in our recommendations.

See the best mattresses toppers we've tested.

What are Best Buy and Don’t Buy mattress toppers?

A quick guide to our mattress topper recommendations.

Best Buy mattress toppers

The double mattress toppers that impress the most in our lab tests become Best Buys. Any that scores 80% or above is a Best Buy and comes with a solid recommendation, although you should still read our reviews to check for any factors that might affect what you buy.

Best Buys typically tick the boxes that members told us were the most important. They will make a difference to the firmness and the pressure distribution and help change body support in most, if not all, sleeping positions - all of which should help to make your mattress more comfortable. Many of you use a topper to extend the life of your mattress, so they should also be easy to wash.

Don't Buy mattress toppers

Mattress toppers that score 45% or less are poor in multiple areas are deemed Don’t Buys and we recommend you avoid them.

Providing hardly any change in firmness, body support or pressure distribution, Don't Buy mattress toppers won’t make much difference to your mattress - so there’s not much reason to recommend them.

How is the Which? score calculated?

The Which? overall score is a percentage. It takes into account only the results of our tests and ignores price. 

This means that all mattress toppers are tested on the same scale, so you can compare any model at any price and know how it measures up against its rivals in key areas. 

We test double mattress toppers only and all are tested in the same way, regardless of the manufacturers’ claims. Our results cannot be transferred to different sizes of topper. 

Weightings and star ratings

A Which? test score is made up of dozens of individual tests and checks, from key factors such as body support and pressure distribution to washability.

To keep things simple, the most important scores are shown as star ratings out of five on the 'test results' tab of each review, so you can quickly work out whether a model is right for you.

The most important test result are based on what Which? members have told us are the most important factors for them when buying a topper. These factors have a greater impact on the overall score.

• Performance (including change in body support and change in pressure distribution) - 55%
• Change in firmness - 40%
• Washability - 5%

We also assess mattress toppers on their stability but don’t include the results of this test in the overall test score.

Our key testing criteria

Below are the key testing categories and how we evaluate each.

Performance

Our performance measures look at how much difference a mattress topper makes compared to our test mattress, and includes our test results for change in body support for each of the three sleeping positions we test, change in pressure and change in firmness.

Key question: Will the mattress topper provide decent body support?

We use state-of-the-art equipment to measure 36 spinal points which represent standing and lying down on the mattresses.

We then measure spinal position when in a side sleeping position, to check that no part sinks too far into the mattress. A good topper will help keep your spine in line and parallel to the mattress.

We also measure a third time to assess how supportive each topper is for people who prefer to lay on their front, when used on a mattress.

Key question: Will the mattress topper provide decent pressure distribution?

A good mattress topper should help make a difference when distributing your body pressure evenly over the surface of your topper and mattress, so that your shoulders or hips, for example, don’t start to dip in one area.

Change in firmness

Key question: will the mattress topper make my mattress softer?

A good mattress topper should be able to alter the feeling of your mattress. In our survey, 47% of members told us they use a topper to make their mattress softer, so we test using a standard mattress and calculate the change in firmness when using the topper with it.

But if your mattress is old or sagging, a topper won’t make much of a difference. You’ll need to invest in a new mattress. Consult our guide to the best mattresses for buying advice.

Washability

Key question: Is the mattress topper washable?

Some toppers have a removable washable cover, which will help keep it in the best condition much more easily. Some toppers can go straight in the machine as a whole.

Our most important piece of advice is to check your care label and make sure you follow the instructions on how to wash, clean or care for your topper.

If you suffer from allergies, opting for a topper that’s washable or, at the very least, has a washable cover, will be a good choice.

Stability

Key question: Will the mattress topper make my mattress less bouncy?

Each topper is assessed to see how well it helps stops movement travelling across the surface of the topper and a mattress. We call this stability.

If you’ve got a really bouncy mattress underneath, a memory foam topper may help to stop this to some degree. But, if you’ve got a mattress that already dips in the middle, even a foam mattress may not make much difference.

Pick the perfect mattress topper with Which? reviews

Trying out a topper in a shop won’t give you much of an idea of how it will work with your mattress at home. Buy the wrong one and you may end up with a topper that won’t make much difference if you’re trying to make your mattress more comfortable or softer. After paying out for a mattress that doesn't suit your needs, you don't then want to pay out for a topper that won't deliver what you need.

That's where our reviews come in. We test all the main types of topper from memory-foam to pocket-sprung or feather and we can give insight on how well it will help support your back when used with your mattress, how much difference it will make to the feel of your mattress and if it helps to make a difference with evenly distributing pressure. 

We test toppers more thoroughly than anyone else. We can tell you everything you need to know including niggling issues you wouldn't otherwise discover until it was too late.

See all our mattress topper reviews.