memory foam mattress density diagram

What’s Memory Foam Density & How Does it Affect my Mattress?

Memory foam density is the mattress equivalent of the offside rule. It’s a vague and unexplained concept for sleepy shoppers.

Does it make a mattress firmer or softer? Does it make it last longer? How do we measure it? And ultimately – does it matter?

Well puzzle no more, because we’re here to answer all of your questions in plain simple English.


What is Memory Foam?

Before we get stuck into density ratings, let’s take a look at the foam itself. Memory foam is made up of a man-made polyurethane foam which softens in contact with body heat and weight. As a mattress material, it provides superior comfort and support, cushioning pressure points for a tailor-made sleep.


What Is Memory Foam Density Rating?

Density is the primary means of measuring the quality of foam. The density measures how heavy the material is compared to its size.

You can find memory foam densities ranging from low (less than 40kg) to high (75kg and above).


How is Memory Foam Density Calculated?

Density is measured in cubic metres (m³) so foam with a density of 60kg will weigh 60kg if you have one cubic metre of it.

A higher density mattress (eg. 75kg) has more foam fitted into each cubic metre so it weighs more (75kg per cubic metre). A lower density mattress (eg. less than 40kg) features a less compressed foam with more air pockets, so it weighs less (45kg per cubic metre).


Is Foam Density Important?

Yes. It’s an important factor in choosing the right mattress but it’s not the be-all and end-all. It’s one of several important features which come together to create the perfect memory foam mattress for you.

Think of your mattress like a sports car. If it has an amazing engine but sub-standard tyres and an unprofessional driver … it’s not going to win the race. Well, mattress density is the same thing. It’s just one factor.


Does It Control How Comfortable My Mattress is?

No. Foam density plays a role in comfort levels, however, mattress depth, composition and support levels are just as influential. And the most important thing by far is finding a mattress which suits and supports your sleeping habits. Back pain sufferers, side sleepers, front sleepers, restless sleepers, heavy sleepers – these habits determine the best mattress for you, and foam density is not the only thing which is different.

For example, hot sleepers may want to choose a lower-density mattress with open-cell foam for a more breathable night’s sleep.


Memory Foam Density and Firmness Levels

While many people believe that a high-density foam equals a firmer mattress, this isn’t always the case. While higher density foam often feels firmer, make sure to check the comfort level of the mattress before you buy as the different layers and types of foams that make up the mattress can all affect the surface feel.


Does Density Control How Long My Mattress Will Last?

Yes, foam density is very important for this. High density foam is more durable and as a result, high density foam mattresses last longer. These high density products usually come with a long warranty (5+ years) as proof of the manufacturers’ confidence.

Memory foam as a material is very durable and can offer long term comfort for all types of sleepers.


What’s the Best Density for a Memory Foam Mattress?

Before we jump into the figures, please remember that the composition of the mattress is just as important – if not more so – than the density of the foam in it. A lower density memory foam mattress which is suitable for you is a lot better than a high density item which is not.

We always recommend getting in touch and having a chat to make sure that your memory foam mattress suits your individual needs.


High Density Foam

Mattresses with a density of 55kg and above are fairly high density products and will last a long time with daily use, making them the best option for your main bed at home. They tend to cost a little bit more – but when you consider the length of time which your new mattress will look after you for, high density foam gives you far better value for money.

We have a wide range of high density memory foam mattresses to choose from.


Medium Density Foam

Mattresses with a top layer of 45kg to 55kg density foam are medium density items, suitable for guest bedrooms which are used on a semi-regular basis, hotels, rental properties and B&Bs.


Lower Density Foam

In terms of the top comfort layer of a mattress (which is usually memory foam), foam with a density of 45kg or below would be considered low density. Low density items are perfect for guest bedrooms which aren’t used all the time.

Such memory foam mattresses won’t last as long but are available at a more affordable price, and are perfect where a long lifespan and the ultimate in quality aren’t necessary.


Foam Density for the Base Layer of a Mattress

When considering the foam density of the bottom/ base layer of a foam mattress, you’re looking for different things in terms of density. This is because base foams are a lot firmer and more supportive than soft mouldable foams which are used in the top comfort layers (memory foam and similar materials) – so you don’t need to pack as much of it into each cubic metre to get the support you need.

Bearing this in mind:

  • Base foam with a density of 30kg/m and below is considered low density
  • 30kg/m to 35kg/m is considered medium density foam
  • High density base foam is anything over 35kg/m


What Memory Foam Density do I Need?

There are several personal factors to consider when choosing the right foam density for you.

  • Bodyweight - Heavier people may want to choose a higher density foam mattress that provides more resistance when they sink into the surface.
  • Price - If you’re on a budget, very high density mattresses may be out of your price range. However, it’s perfectly possible to find a comfortable and supportive memory foam mattress for less.
  • Back and joint pain - Higher density foam mattresses can help to ease aches and pains by distributing weight evenly across the surface. Look for orthopaedic foam mattresses if back pain is an issue for you.
  • Sleeping position - If you sleep on your side, you may want to choose a lower density foam that provides extra cushioning and contour for your shoulders and hips


How Do I Find Out The Foam Density of a Mattress?

A lot of mattress suppliers aren’t as forthcoming as we are when it comes to the density of their memory foam mattresses and products. It’s always concerning when a supplier hides this information. It’s a bit like buying burgers and not knowing what meat they contain; or splashing out on a new laptop without knowing how many pixels it will display.

Any reputable supplier will tell you what density foam they use in their items. We list our foam densities on the product page for complete transparency when you’re making your purchase. If a supplier won’t tell you the density of the foam in their product then it’s safe to assume it’s not very high and you should be wary of buying it from them!

Find the right mattress for you! We have a range of exquisitely comfortable single, double and king size memory foam mattresses, plus many more sizes and collections available.

Browse our high-quality memory foam mattresses here.

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