5 Tips For Buying The Best Memory Foam Mattresses

I imagine by the time you’ve reached this guide to memory foam mattresses you’ve already looked at several dozen mattresses, each with a more baffling description than the last.

You’ve looked at cross sections of foam and polysomething and you’re trying to work out what ‘density’ you need.

Take a deep breath, I’ve been there fellow shopper. Here’s our guide to buying a good quality memory foam mattress, and I promise not to use loads of ridiculous words that will make you feel you are back in high school double science lessons…

Hotel bedroom with duvet
Need a lie down after spending hours searching for a mattress?

1. (Some of) the best memory foam mattresses have won awards and rave reviews

One way to speed up the memory foam mattress buying process is to pick one with great consumer reviews or industry awards.

Here are seven highly rated memory foam mattresses:​

Nectar Sleep Mattress (£600) – several awards, 4.4/5 from customers on TrustPilot after thousands of reviews. The Nectar Sleep stands out thanks to its 365 night trial period and its ‘forever guarantee’ (with some Ts and Cs of course). It also offers a 3cm layer of memory foam on top of other foams. You’ll find that some cheaper memory foam mattresses only have a very thin layer. It is medium/firm and some customers find that it is too firm for them.

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The Nectar Sleep mattress has the longest warranty and trial period of any memory foam mattress we’ve found
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Ergoflex 5G (£483), the trial period with the Ergoflex 5G is 30 nights, so not as long as others. However, the mattress has been on the market in the UK for much longer and it gets a spectacular score of 4.8/5 on TrustPilot. It comes with a 10 year warranty, which is quite standard for a memory foam mattress of this price. Much like the Nectar Sleep it is rated as a medium/firm mattress.

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Emma Original Mattress (£299), one of the biggest selling mattresses on the market in the UK (although exact figures aren’t published). In 2020 they increased the length of their trial period from 100 nights to 200 nights which means you can try it out in winter and summer before deciding if it’s right for you. Again, it’s a reasonably high scorer on TrustPilot, with an average score of 3.9/5 when we checked. The Emma mattress has won several awards and is considered medium firmness, so slightly softer than the Nectar Sleep and Ergoflex 5G.

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Silentnight 3 Zone Memory Foam (£202 for a double memory foam mattress) – this is a budget priced mattress from the biggest name in the UK mattress market. The most notable cost cutting has been made by making this mattress thinner than most others. However, it remains a popular option and the shallower than average depth might actually be a good thing if you are looking for a mattress for a trundle with a limited space. Rated as a soft/medium mattress, making it softer than the Emma Mattress. ​

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Dormeo Memory Plus (£343 for a double memory foam mattress) – awarded a Best Buy award by Which? magazine. Dormeo is an Italian brand which sells some innovative and expensive memory foam mattresses. However, they also sell this budget-friendly model which is considered medium firmness, so similar to the Emma mattresses. 

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Tempur Original Elite (£2019 for a double) – the original memory foam mattress company, which took inspiration from materials used by NASA to develop its mattresses. This model is medium firmness but they also sell mattresses which are softer and firmer. If you’re really feeling flushed you can buy Tempur adjustable bases which will massage you before you go to sleep. Read our full Tempur guide for softer or firmer alternatives.

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2. (Most of) the best memory foam mattresses are thick

An indicator of the quality of a memory foam mattress is its thickness. Cheap memory foam mattresses are about 15cm deep, whilst top quality and highest priced mattresses go up to about 30cm. 

As you might have guessed, the general rule is that you’ll pay more for a thicker mattress.

For example, these three mattresses feature in our guide to Silentnight mattresses:

  • The Silentnight 3 Zone Memory Foam mattress gets good reviews, but it is only 18cm deep, hence the £202 price tag.  
  • The Silentnight 7 Zone Memory Foam mattress is 20cm thick and costs about £100 more.
  • The Silentnight Studio mattress is £599 and is 26cm deep.

We can back up this theory with some data. We looked at the price and depth of mattresses in our guide to the best memory foam mattresses and came up with this graph:

Graph showing that thicker memory foam mattresses cost more
Our graph shows that thicker memory foam mattresses tend to cost more

For anyone currently figuring out what the graph shows, let me give a bit of analysis. 

Broadly speaking, there is a correlation between the cost and depth of the memory foam mattresses in our comparison. The data is affected quite significantly by the Tempur mattress which costs three or four times as much as the rest but obviously isn’t triple the depth. Without that inclusion it would be a much clearer correlation. Even so, we can see a pattern.

Bear in mind that thick memory foam mattresses are very heavy. The super king size version of the Tempur Sensation Elite weighs 50kg (11 stone) and needs rotating regularly. There would be a certain irony in getting a bad back from turning your £2000+ mattress…

Getting the firmness right

​On a sort-of related note, make sure that you buy a memory foam mattress which is the right firmness for you. As a general rule, heavier people will need a slightly firmer mattress than lighter people and will get more benefit from a deeper mattress. Also, people who sleep on their side tend to go for slightly softer mattresses because their shoulders and hips sink into the mattress more than someone who sleeps on their back. 

Rather frustratingly, there’s no industry agreed standard for mattress firmness but if you combine those two things together then you can have a guess of whether you need a soft, medium or firm memory foam mattress. For example, a heavier person who sleeps on their back will certainly want a firmer mattress than a lighter person who sleeps on their side.

3. The thickness of the ‘top layer’ of a memory foam mattress is important

There’s an old trick in catering where you bring out the best wine at the start. Once everyone is tipsy, you swap it for cheap wine and no-one notices.

Mattresses are a bit like that – the best quality and most expensive materials go on the top, and then cheaper materials are used underneath to pad it out. With a memory foam mattress, it’s worth looking at how thick the top layer of memory foam is. ​

For example, the Simply Sealy Memory Mattress (£519) has a 2cm layer of memory foam whilst the Ergoflex 5G (£966) has a whopping 9cm layer of memory foam. I’m not saying that the Sealy mattress isn’t a good one (it has very good reviews and it offers a lot for the price) but the Ergoflex uses considerably more memory foam.

Ergoflex 5G mattress
The Ergoflex 5G mattress has a 9cm deep layer of memory foam – much more than some cheap mattresses

The general consensus is that you don’t necessarily need to have a massive layer of memory foam for a mattress to be comfortable and supportive, but if you’re paying a lot for a mattress with only a tiny layer of memory foam then you probably aren’t getting a good deal.

It gets a bit more complicated when you start talking about pocket sprung mattresses with a memory foam topper, but the rule applies to a mattress which is entirely made from different types of foam.

To show the range in the way memory foam mattresses are designed we created this bar chart showing the depth of memory foam used in six popular mattresses. As you can see, the range from our selection goes from 3cm with the Silentnight 3 Zone up to 12cm with the Tempur Original Elite . 

Best Mattresses Guide bar chart showing memory foam layer depth
Comparison of Vispring prices and number of pocket springs

However, it wouldn’t be fair to leap to the conclusion that the mattresses with more memory foam are necessarily offering something ‘better’.

What the graph doesn’t show is that The Emma Mattress and Studio by Silentnight both utilise alternative layers to work alongside the memory foam layer which they reckon will provide a create a better night’s sleep. The Studio by Silentnight uses 4cm of ‘Geltex’ whilst the Emma Mattress has a layer of Airgocell, both of which are designed to help with breathability and temperature control. 

Alongside that, whilst a lot of people think of Tempur as being a memory foam brand (and we include in some of our memory foam guides) the company itself says that their product is different to what they call ‘standard memory foam’. The description of the Tempur Original Elite actually refers to two layers of ‘Tempur comfort material’ (3cm) and ‘Tempur support material’ (9cm).

It isn’t entirely accurate to consider this a 12cm layer of memory foam, as the company itself offers some quite strong criticism of ‘standard memory foam’ such as saying on its website that ‘It is our opinion that standard memory foam mattresses are not very effective when it comes to relieving pain and pressure’. 

What’s the cover story?

Another related thing to consider is that the best mattresses have a breathable cover. They might be made from something naturally breathable like cotton or a ‘breathable’ manmade material.

​If it’s made from bog-standard polyester without any mention of breathability then it’s not so good, and it might add to the problem of some memory foam mattresses feeling too hot. 

There are also lots of impressive sounding names for the outer material on a mattress (hypoallergenic, organic etc…). I haven’t yet found anything independently written which says that any of these hold magical powers, but just make sure it is something breathable.

4. The best mattresses have a decent warranty (and some have a trial period)

A long warranty is no guarantee of quality, but there’s a correlation between the price of a mattress and how long the warranty lasts for. To use the same example as before, the Silentnight 3 Zone Memory Foam Mattress (£202) comes with a 3 year warranty whilst the pricier Silentnight Studio mattress (£679) comes with a 5 year warranty.

In recent years, memory foam brands have been trying to out-do each other by offering even longer warranties. 

Several memory foam mattresses now come with a 10 year guarantee such as Ergoflex 5G (£966) and the Emma Original Mattress (£299).

Meanwhile, the Nectar Sleep Mattress has gone even further by offering a ‘forever’ warranty. I’m pretty sure no-one is going to able to beat that.

Obviously, there is small print to read with these things, as there is some variation in what is covered. 

Emma Mattress with a 200 night trial
The Emma Mattress has a 10 year warranty

Another thing to consider when buying a memory foam mattress is whether or not it comes with a risk free trial period. 

Again, this is no guarantee of quality but it certainly makes it more appealing to the buyer. Instead of spending a few awkward seconds lying down in a showroom, you can try out a mattress for weeks or even months before deciding if you want to keep it. If you send it back, they are usually given away to a charity or recycled.

Most home trial periods allow you to get a refund if you don’t like the mattress whilst a few will only offer a swap for a different mattress. Sometimes there are hoops to jump through, such as always using a mattress protector so have a read of the terms and conditions before you buy it.

At the time of writing, some options include:

For more ideas, see our guide to mattresses with a free trial.

Data showing trial period length of competing UK mattress brands
Our bar chart shows the range of trial periods on memory foam mattresses – but check if the trial allows you to return it or swap it

5. (Most of) the best memory foam mattresses are ‘dense’

Feel free to nod off for this bit, it gets a bit technical. 

Some memory foam mattresses come with a ‘density’ rating. It will probably be somewhere between 35kg/m3 to 85kg/m3. If the numbers don’t look like that, then you’ll need to get the calculator out to do some conversions of imperial to metric (or just give up and watch some telly).

It’s a bit complicated, but the main thing you need to know is that higher numbers are generally better, but it gets to a point where you don’t gain much from it being really dense.

From the many guides I’ve read, most people say that 50kg/m3 – 60kg/m3 is absolutely fine. A very low score suggests it is cheap.

Honestly though, I wouldn’t get too obsessed about density ratings because a lot of mattresses don’t actually give the rating as part of their specification. 

You might also see a ‘firmness’ rating or an ‘ILD’ rating on a memory foam mattress. If you’re interested, it stands for Indentation Load Deflection, but my guess is that you don’t care…

These ratings don’t indicate quality, but they tell you what they will feel like to lie on. ​

One final thing…

There seems to be two schools of thought when it comes to memory foam mattress design. This may be a whole new level of boring for you, but let’s plow on regardless.

Some of the ‘bed in a box’ mattresses such as the Emma Original Mattress use memory foam in the middle of the mattress, like a slice of delicious visco-elastic ham in a sandwich. As a result, they don’t have such a significant ‘sinking feeling’ which you get with some memory foam mattresses. Some things I’ve read reckon this design means that you are less likely to feel too hot.

Meanwhile, some of the other ‘bed in a box’ mattresses such as the Nectar Sleep Mattress and the Ergoflex 5G use memory foam as the top layer, but also use clever techniques which they say will keep you cool.  For example, the Nectar Sleep has a ‘cooling cover’ and ‘smart memory foam’ which ‘regulates your body temperature’ whilst the Ergoflex 5G has a ‘Cool Sleep Airflow System’ which ‘allows for air-flow and temperature regulation’.

For us shoppers, it’s worth realising that all of those brands mentioned above get very strong reviews and have won awards from experts. When I checked, they were all scoring between 4.2 and 4.6/5 on TrustPilot (see the full run down in our beginners’ guide).

As mentioned earlier, all of those ‘bed in a box’ foam mattresses mentioned above (and several others) are sold online and offer an appealing free trial ranging from one month to one year, so you can send it back if you’re not happy (check the small print, obviously).

A small number of other memory foam mattresses which you can try out in a shop offer something similar (Tempur do a 100 night trial and cost about £2000ish).