The Mattress Firmness Scale Explained: How to Choose the Right Firmness Level?

There’s probably no other characteristic of a mattress that has as significant a bearing on how comfortable and suitable it is for you as its firmness.

In this guide, you’re going to learn about the mattress firmness scale and what the different levels of firmness mean in terms of comfort and mattress performance.

You’re also going to learn how to choose the right mattress firmness based on your unique needs and preferences, including your size, weight, and dominant sleeping position, and we’ll answer frequently asked questions about mattress firmness.

What is Mattress Firmness?


Mattress Firmness simply refers to the feel of a bed when you lie down on it — whether it feels hard, soft, or somewhere in between. It is essentially describing the feel of the mattress in terms of comfort.

While there is a firmness scale, and manufacturers will specify mattresses as being anywhere between soft and firm, it can be quite a subjective thing.

Because firmness is all about feel, it is up to each individual to interpret firmness as it feels to them.

Why Should You Care About Firmness and Comfort Level?

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Firmness is probably the single most crucial aspect of a mattress and the metric by which most beds are chosen, simply because firmness is the most significant contributor to a mattress’s comfort, and it’s the first thing you notice.

If you lie down on a new mattress, you will immediately be able to tell if it’s too hard, too soft, or just right.

Getting the wrong firmness can be highly detrimental to your sleep quality and your health. For instance, if you suffer from back pain, a mattress that is too firm may not offer the right level of support and pressure relief.

In contrast, if you sleep on your side, a mattress that is too firm may mean you suffer uncomfortable pressure points due to it not fully conforming to your body and evenly distributing weight.

Simply put, pick the wrong firmness, and you’ll know about it. You’ll just be plain uncomfortable and may even suffer health effects.

So firmness is most definitely one of the characteristics of a mattress you should care about the most.

What’s the Difference Between Firmness & Support?

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As mentioned already, firmness refers to the feel of a mattress — how soft or hard it is when you lie down on it. Support, on the other hand, refers to how well a mattress keeps your spine in alignment.

If you think of something whose job is to act as a support — for example, piles under a house, what are they doing? They hold something up (in this case, a house), offering an equal and opposite reaction to the weight bearing down on them.

It’s the same concept when it comes to mattress support. The right mattress will offer a level of ‘pushback’ against your weight and hold your body in such a position that your spine is in proper alignment — essentially a “neutral” position.

This means your mattress must be able to bear the weight of your body, especially at points where the most weight is concentrated, like the hips and shoulders, without allowing them to sink too deeply.

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The Mattress Firmness Scale

Mattresses will always fall somewhere along the mattress firmness scale. The scale is numerical, running from 1 to 10. Here’s how firmness is measured:

Firmness ScaleMattress Firmness

Mattress Firmness Levels in Detail

1Soft to Medium-soft

Softer beds are better suited to light individuals who weigh around 130lb or less because they provide adequate support for this weight range, but likely no one else.

Heavier individuals are likely to sink too deeply and ‘bottom out’ on a very soft mattress — they usually are just not supportive enough.

Soft mattresses will hug and conform to the sleeper’s body more than a firm mattress.

It is often the firmness that determines whether a mattress has this ‘sleeping in’ the mattress feel vs. an ‘on top of it’ feel. Softer mattresses can often feel more challenging to move around or reposition on.

There is some irony when it comes to extra soft mattresses. Often, soft mattresses will be more expensive, both because they use expensive materials in the form of comfort foams and will usually have more layers to accommodate all the comfort foams.

But soft mattresses also tend to have shorter lifespans because the less-dense foams typically deteriorate quicker than denser, firmer foams.

So if your preference is for a soft bed, be prepared to spend more and replace it more often.

Softer beds are usually better suited for side sleepers who need extra pressure relief but are generally not great for back and stomach sleepers or heavier people.

illustration of a bed

2Medium to Medium-firm

This is the range that generally suits the preferences of most people. Mattresses with medium firmness characteristics usually provide a good balance between comfort and support.

This balance makes for broad appeal — Medium and Medium-firm mattresses are usually best for people who fall in the average weight range (between 130-230lb).

The level of both sinkage and conforming (how the mattress ‘hugs’ your body) will typically be lower than a softer mattress but higher than firmer mattresses.

Medium to Medium-firm mattresses are generally suited to most sleeping positions.

While this will vary from mattress to mattress, there’s usually enough of a balance between comfort, support, and pressure relief that back and stomach sleepers should feel enough support, while side sleepers should have sufficient pressure relief.

A more balanced feel means Medium to Medium-firm mattresses generally have fewer comfort foam layers or use thinner layers, taking away that plush, sink-into-the-mattress feel while still offering a decent buffer against the denser support layers below.

The life expectancy of mattresses in the medium range is higher than for softer mattresses but not as high as firmer ones. They should generally fit within the 7-10 year average.

Pricewise, Mediums will typically use less comfort foam layers, meaning they should be cheaper in general than a soft mattress, but this will vary by brand and retailer.

illustration of a bed


The main characteristic of mattresses in the Firm range is they do not have as much ‘give’ — they do not sink as deeply as softer mattresses.

Depending on body weight, some firm mattresses may only offer very minimal sinkage, of any at all, meaning they tend to well and truly give the feeling of sleeping ‘on top of’ the bed rather than being enveloped and being held ‘in’ the mattress.

Firmer mattresses are best suited to heavier than average people, those who weigh over 230lb. This is because they offer superior support with a lot of pushback to compensate for heavier weight, without excessive sinkage that a softer mattress would allow.

Lighter people sleeping on a firm mattress may find that the level of conforming is not close enough to provide enough support or pressure relief and correct spine alignment.

In contrast, heavy people will sink deeply enough to get the contouring benefits of the thinner comfort layers.

Firm mattresses are generally not a good choice for side sleepers due to insufficient pressure relief. Still, stomach and back sleepers should find adequate support and good spine alignment due to areas like the hips and midsection not sinking too deep.

Firmer mattresses tend to use denser foams that are more hardwearing and less prone to forming permanent indentations and sagging. The lack of plush comfort foams also means they can sometimes be cheaper.

illustration of a bed

How to Choose the Right Mattress Firmness for You?

Two things that have a major influence over what level of mattress firmness is going to feel right for you are the position you primarily sleep in and how much you weigh. Let’s take a look at the firmness level you should be looking for in a mattress based on these.

If You’re a Back Sleeper

When lying on your back on a flat surface, your spine is naturally in a neutral position. So, if you’re a back sleeper, you will want a bed that is firm enough that areas such as your hips and shoulders are not going to be allowed to sink lower than the rest of your body.

At the other extreme, you don’t want your body to create an arch where your lumbar region is unsupported.

There needs to be enough softness that the comfort layers allow a little sinkage in order to conform to the shape of the sleeper’s body without letting it sink too deep.

The majority of back sleepers will choose a mattress in the Medium-soft to Firm range. Mattresses at the softer end will be better suited to light back sleepers, and firmer beds suited to heavier sleepers. Aside from firmness, support is key for back sleepers.

If You’re a Side Sleeper

Side sleepers have a very specific requirement due to their sleeping position — pressure relief. This is because when lying on your side, the body’s weight is concentrated in two main areas — the hips and shoulders.

The hips and shoulders are bony and hard, and when on the side, have a relatively small surface area in contact with the bed.

This means there is a lot of pressure on these two areas, and this pressure can build up to the point of becoming extremely uncomfortable.

So, side sleepers need a mattress with a soft enough surface that will conform to the body, especially the shoulders and hips, while having enough support to distribute body weight evenly, taking pressure away from the hips and shoulders.

Aside from pressure relief, firmness needs to be at a level where the spine is not out of alignment due to being too firm and not allowing enough sink.

Softer mattresses are better, but they still need enough support to compensate for any sinkage. Mattresses in the Soft to Medium-firm range will be best for side sleepers.

If You’re a Stomach Sleeper

Stomach sleeping can be pretty problematic from a pain point of view, especially when it comes to the lower back. Stomach sleepers are similar to back sleepers in that when lying flat; the spine is in a neutral position.

But, a mattress that is too soft on top and allows the hips to sink below the rest of the body throws that alignment out and puts pressure on the lower back.

Like back sleepers, stomach sleepers need a firm enough mattress that won’t let the midsection sink too deep but still has enough softness that the surface will conform to the body and cradle the areas that need it.

Most stomach sleepers will choose a mattress in the Medium-soft to Medium-firm range. Heavier stomach sleepers may even go up to a Firm.

If You’re Light Weight

Light sleepers (130lb and under) tend to be a match for softer mattresses. Lighter individuals need enough plush softness to sink enough that the comfort layers conform to their body.

Firm mattresses can cause pressure points for light people because they tend to sit on top of the bed rather than sinking into it and having it conform to them.

Without this conforming, the weight is concentrated in the heaviest areas that are in contact with the mattress. This is what causes pressure build-up.

In order to get the level of contouring needed, most lightweight sleepers will choose a mattress in the Soft to Medium range.

If You’re Average Weight

Average weight people in the range of 130-230lb need a balance between comfort level and support.

There needs to be enough of a plush comfort layer to allow a little sinkage and contouring, with enough support underneath to prevent sinking too far and help with pressure relief.

Average weight people probably have the widest range of mattresses to choose from, and chances are there’s a selection of mattresses out there that will suit your preferences if you are in this weight range. Beds in the Medium-soft to Medium-firm range will likely be the best match.

If You’re Heavy Weight

Heavy people who are 230lb+ need a mattress with plenty of dense, sturdy support. Heavier individuals need a bed that isn’t going to suffer wear and tear prematurely, but that doesn’t mean it has to have rock hard firmness.

In saying that, firmer beds will suit heavier-than-average people in general due to the increased pushback they generally have. They tend to have thinner comfort layers that, while still conforming and contouring the body, won’t allow deep sinkage.

Firmer mattresses tend to have ‘transition’ layers or springs that act as a buffer between the soft layer above and the hard support layers below.

If a heavy person has a mattress that allows them to sink too deep, this can cause them to fully compress the comfort layers and come to rest on the more rigid materials below, meaning they suffer inadequate support and pressure points — not to mention plain discomfort.

The mattresses that are likely to be the best fit for heavy people will be in the Medium-firm to Firm range.

The Problem With Firmness Extremes

an illustration of a mattress with arrows

Even though the firmness scale is measured between 1 and 10, it is unlikely you’d ever come across a mattress that sits at the extreme of either end of the scale.

Why? Because level 1 or 10 would be so soft or so firm, they’d pretty much be at the point of ridiculousness and not actually suitable for anyone but the rarest of cases. A mattress with level 1 softness would have an extreme level of sinkage while not providing any meaningful support.

A mattress with level 10 firmness would nearly feel like sleeping on a tabletop — extreme pushback levels with next to no sinkage or conforming properties and extremely thin soft comfort layer.

What Does One-Firmness-Fits-All (or Universal Comfort Level) Mean?

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The label ‘Universal Comfort’ is pretty self-explanatory — it’s a claim that a mattress will be suitable for all sleepers, regardless of preference. Which, if you think about it, is a pretty silly claim; there’s no mattress that’s going to be able to cater to everybody’s preferences and needs.

Essentially Universal Comfort mattresses are ones that appeal to the broadest range of sleepers (not all) — they’re essentially a mattress for the ‘average’ person.

80% of people prefer a mattress in the Medium to Medium-firm range, so Universal Comfort mattresses will fit somewhere within this range.

Aside from firmness, One-Firmness-Fits-All or Universal Comfort mattresses are also designed to have a comfort level that’s compatible with all sleeping positions. They are usually very balanced, having levels of sinkage, contouring, support, and pressure relief that should be comfortable for the average person no matter how they sleep.

Our advice is that you shouldn’t necessarily shy away from Universal Comfort mattresses, but don’t buy one simply because you think it will be suitable just because it is classified as Universal Comfort. Put it through its paces like you would any other mattress.


Does Memory Foam Always Mean Soft?

No. Memory foam can come in a range of firmnesses. Firmness is determined by what is known as the foam’s Indentation Load Force Deflection, known as either IFD or ILD.

This is not a measure of the foam’s density, as the same density foam can have different IFD.

IFD/ILD is measured using the force in pounds required to compress a foam sample by 25% of its original height.

The lower the IFD, the softer the foam, and the higher the IFD, the firmer the foam is. Base foams typically have both higher density and higher IFD, while comfort layers will have lower IFD.

What Does ‘Plush’ Mattress Mean?

‘Plush’ is a term that simply refers to something that is soft and luxurious.

A plush mattress is one that falls at the softer end of the scale, which allows a good amount of sinkage and provides a deep ‘hug.’

Plush mattresses have a lot of cushioning but still provide a suitable level of support and are generally especially suitable for side sleepers.

Does the Firmness Level Affect Durability?

The firmness level of a mattress generally affects its durability. Softer mattresses typically use thicker layers of soft comfort foam, and this foam is more susceptible to developing permanent indentations and sags. Firmer will generally have a longer expected lifespan.

What if My Partner & I Have Different Firmness Preferences?

Differing partner preferences can be a significant issue when it comes to firmness. One solution could be to compromise and go with a mattress that is ‘ok’ to both partners — but this likely means neither will be totally happy.

Aside from sleeping in separate beds, the best solution would be to look at a ‘split’ mattress — that is, a mattress made up of two separate smaller mattresses of differing firmness.

Are Certain Mattress Types More Firm?

In a word, no. Regardless of the type of mattress, it is the materials and way it is constructed that determines the firmness.

You should never make assumptions about firmness based on the type of mattress; as always, testing each mattress out yourself is the only way to ensure you’re getting the right firmness for you.

What if I’m not sure what firmness level I want for my mattress?

If you are unsure what firmness level is going to be right for you, there’s really no way around it — you’ll need to test some mattresses out for yourself.

You can try out mattresses in a showroom to get a gauge on what feels comfortable to you initially, but you’ll need more than just lying on a bed in a showroom to know for sure.

If you have an idea of what firmness level may be right for you, make sure to go for a mattress that is free and easy to return for either a refund or exchange.

Many ‘mattress-in-a-box’ companies offer generous risk-free trial periods that allow you to try the mattress out at home for anywhere between 90 nights to a full year.