What density should I choose for my mattress?

What density should I choose for my mattress?

To understand how to choose your mattress, it's important to understand a few technical aspects. To choose the right foam or latex mattress, it is essential to consider its density. Knowing when to change your mattress is also important for maintaining optimum sleep quality.

To understand how to choose your mattress, it's important to understand a few technical aspects. To choose the right foam or latex mattress, it is essential to consider its density. Knowing when to change your mattress is also important for maintaining optimum sleep quality.

The density of your mattress is an important factor that you want to be sure of when buying a mattress that will give you good support - in other words, support that perfectly respects the natural alignment of the spine and cervical vertebrae.

Different mattress types and technologies

The best mattress is the one that perfectly matches your morphology, your tastes and your specific needs. That's why it's important to know the basic technologies when choosing a mattress. A mattress comparison can help you see more clearly between the different options available.

The term foam mattress is fairly broad: it covers both entry-level mattresses made exclusively from polyurethane foam and models combining a polyurethane structure with a layer of memory foam. Memory foam reacts to body heat to mould perfectly to your curves and give you good support.

Although they are among the best mattresses for preventing and relieving back pain, it's worth looking at the advantages and disadvantages of memory foam mattresses before making your choice. This type of mattress is very supportive and adapts to almost all body shapes, but can be considered too soft. If you prefer a firm or medium-firm mattress, it may be preferable to opt for a pocket-spring mattress.

Pocket springs are firmer, but also more responsive than foam, so this mattress is more suited to sleepers who tend to move around a lot during their sleep, and it gives you perfect sleeping independence. If you're wondering which mattress to choose for back pain, it could well come down to foam or spring!

Thickness and density: what's the difference?

Thickness should not be confused with mattress density. In fact, density is a criterion that exclusively concerns foam or latex mattresses. Measured in kilos per cubic metre (kg/m3), it corresponds to the amount of material on a given surface, and determines the mattress's level of comfort.

The choice of density depends mainly on 3 criteria:The number of sleepers: 1 or 2 people;The morphology of the sleeper(s);The desired level of firmness.In the case of foam mattresses, it is advisable to opt for a foam density of 30 kg/m3 for very soft comfort to 50 kg/m3 for firmer support. In the case of latex, opt for a density of 28 to 50 kg/m3.

Is a thick mattress necessarily a good mattress?

A thick mattress is often seen as the guarantee of a good night's sleep. Of course, it's not that simple!

A thick mattress is in fact comfortable... if it's of good quality! That's why it's essential to know where to buy a mattress, and to favour specialist brands.

Buying a quality mattress is good. But it's even better if it's perfectly suited to your needs! There's no such thing as one-size-fits-all bedding, and for maximum comfort, your slat base and mattress must be just right for you. So you need to choose a mattress size that's specifically adapted to your body shape and the number of sleepers. Allergy sufferers can opt for foam or latex mattresses, which are hypoallergenic.

As for which mattress to choose for back pain, that depends. Depending on the origin of your pain, a firmer or softer support is recommended - don't hesitate to ask your physiotherapist or osteopath for advice! As a general rule, high resilience memory foam is recommended, but this is not always the case. While the resilience of the foam means that it moulds perfectly to your shape, it is not as well ventilated as latex, for example, which can be a problem if you perspire.

Mattress density, what exactly are we talking about?

The density of a mattress is measured in kilograms per cubic metre (kg/m3). It corresponds to the amount of material on a given surface. This criterion applies exclusively to two types of mattress: foam mattresses and latex mattresses.

In the case of spring mattresses, we're interested in how many pocket springs make up a good mattress.

The density of the foam (or latex) determines the firmness of a mattress, but also it's longevity: the denser it is, the longer it will last.

Please note: density should not be confused with the thickness of the mattress!

When buying a foam or latex mattress, you need to choose its density carefully according to the build of the sleeper(s) for whom it is intended.

What density for a memory foam mattress?

The density of a foam mattress varies from 25 kg/m3 to over 60 kg/m3.

There are two types of foam:

  • Polyether foam, with a density of up to 28 kg/m3;
  • and high-resilience polyurethane foam, with a density of between 28 and 60 kg/m3.
Foam density
20 to 25 kg/m3
25 to 35 kg/m3
35 to 50 kg/m3
Recommended use
Additional/spare bed
Extra bed or cot (up to 13 years)
Adult bed
Foam density
Recommended use
20 to 25 kg/m3
Additional/spare bed
Foam density
Recommended use
25 to 35 kg/m3
Extra bed or cot (up to 13 years)
Foam density
Recommended use
35 to 50 kg/m3
Adult bed

To determine the ideal density of your foam mattress, take into account your weight and height. A sleeper over 1.80 metres tall should opt for a model with a density of 45 to 50 kg/m3 for firm support. If you still want soft comfort, opt for a mattress with a layer of viscoelastic memory foam. The choice of density also determines how long the mattress will last:

Densité de la mousse
20 to 28 kg/m3
28 to 30 kg/m3
30 to 40 kg/m3
40 to 50 kg/m3
> 50 kg/m3
Average mattress life
2 years
3 years
5 to 6 years
6 to 8 years
10 years and over
Densité de la mousse
Average mattress life
20 to 28 kg/m3
2 years
Densité de la mousse
Average mattress life
28 to 30 kg/m3
3 years
Densité de la mousse
Average mattress life
30 to 40 kg/m3
5 to 6 years
Densité de la mousse
Average mattress life
40 to 50 kg/m3
6 to 8 years
Densité de la mousse
Average mattress life
> 50 kg/m3
10 years and over

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What density for all your mattress types?

What density for all your mattress types?

What density for a latex mattress?

The firmness of a latex mattress depends partly on its composition. However, the density of the mattress is decisive. If the density is between 65 and 75 kg/m3, the support will be rather soft. Between 75 and 80kg/m3 the support will be firm. Above 80kg/m3, the support will be very firm. To fine-tune your choice, you need to find the right balance between your morphology, taking into account your height and weight, as well as your taste in bedding.

What density for a baby mattress?

Choosing a baby mattress is not just a question of comfort: it's also a question of safety. Specialists therefore recommend a fairly firm mattress. In the case of foam mattresses - the most common on the market - it is advisable to choose a density of 30 kg/m3. More and more young parents are turning to natural latex mattresses. In this case, a density of 70 kg/m3 is recommended.

What density for a mattress topper?

A mattress topper is an invaluable ally for adding a touch of extra comfort to your bedding. Its density is an essential criterion for making the right choice. But, contrary to what you might think, this has nothing to do with choosing a mattress, and as in the case of a mattress, the higher the density of the foam, the firmer the mattress topper, and the longer it will last. So what's the difference? In the way the density of the foam is indicated, for a start! The mattress topper is only a few centimetres thick. Its density is therefore calculated in grams per square metre (gr/m²). It varies from 300 gr/m² to 700 gr/m². Next, the density of the mattress topper is no longer chosen according to your build, but according to the comfort you are looking for. So, if you think your mattress is too firm, you can opt for a 300 to 400 gr/m² mattress topper for soft comfort. If, on the other hand, your mattress is too soft, opt for a 600 to 700 g/m² mattress topper.

What criteria should I take into account when choosing the density of my mattress?

Your morphology is the essential criterion for choosing the density of your mattress. However, as the density of the foam or latex determines the firmness of your mattress, it's a good idea to take other factors into account to refine your choice.

What's your favourite sleeping position?

That's right: when choosing your mattress, it's essential to consider your preferred sleeping position! If you sleep on your stomach, a firm mattress is recommended. If you sleep on your side, on the other hand, a medium-firm mattress is recommended. In this position, your hips exert pressure on the mattress. Normally, your hips should sink into the mattress. If the mattress is too soft, your hips will sag excessively. If it's too firm, on the other hand, it will push them back. In either case, the natural alignment of the spine is no longer respected!

Mattress density and comfort zones

You may have heard of pressure points, but do you really know what they are? There's nothing complicated about it: the weight of the body is not distributed evenly, so some limbs are heavier than others. This is mainly the case for the head and hips. That's why the latest generation of mattresses have comfort zones - areas where the density of the foam is adapted to give you good support. For maximum comfort, it's a good idea to combine foam or latex density adapted to your body shape with this technology!

Foam density and back pain

Choosing the density of your mattress is particularly important if you suffer from back pain. We often hear that a firm mattress is recommended for back pain: so much so that our grandmothers used to recommend sliding a board under the mattress. But that's not really a good idea, is it?

Your mattress should be neither too soft nor too firm. For maximum comfort, it's advisable to play with both the density of the foam or latex and the thickness of the mattress. So opt for a density of 35 to 50 kg/m3 for a foam mattress and 75 kg/m3 for a latex mattress, choosing a mattress at least 18 cm thick.

If you'd like to find out more about mattresses, check out our other advice pages on these subjects:
How to clean a mattress
Mattress lifespan
Disinfecting mattresses
Mattress recycling

If you are in a particular situation, these topics may be of interest to you:
Removing blood stains from mattresses
How to remove old stains from a mattress
How to clean rings from a mattress
How to clean a yellowed mattress
How many pocket springs make a good mattress
What mattress for children
Mattress for pregnant women
What mattress for overweight people?