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How to Choose Mattress Firmness Properly in 5 Steps

Buying a new mattress can be a confusing and overwhelming task.

That’s why in this guide, I’m going to explain what mattress firmness is, how it differs from mattress support, and how to choose the right mattress firmness so that you don’t end up with unwanted aches and pains night after night.


What is Mattress Firmness?

Mattress firmness is basically the initial ‘feel’ that you get when lying down on the mattress.

More specifically, mattress firmness pertains to the degree of surface tension conferred by the uppermost layers of the mattress.

This in turn affects the amount of pressure that you can feel when lying on the mattress.

For example, a ‘firm’ mattress would have a higher degree of surface tension than a ‘soft’ mattress and you would more than likely feel a greater level of resistance.

This may lead you to think that a softer mattress would be more comfortable but this might not be the case for you because there are several factors such as your sleeping position, body weight, and the type of mattress materials being used that will ultimately dictate your ideal mattress firmness.

I’ll walk you through the process of uncovering the right mattress firmness for you in the second half of this guide.

But first, I want to clear up the confusion between mattress firmness and mattress support.


Image source: stock image used with permission.

Mattress Firmness v Support – What’s the Difference?

Mattress firmness and support are NOT the same thing.

Mattress support refers to the degree by which the lower layers of the mattress are able to keep your spine in alignment.

Conversely, the mattress firmness is the feeling and amount of pressure relief conferred by the uppermost layers of the mattress.

Do not make the mistake of assuming that a soft mattress has less support than firm mattress either.

Because it’s the lower layers that dictate the support.

For example, you could have a hybrid innerspring mattress with a soft upper layer and still have great support thanks to a high number of hourglass-shaped springs with a low coil gauge in the lower layers.

On the other hand, you could quite easily end up with a mattress that feels firm on top but has poor supporting layers and so your spine drops out of alignment and could result in back pain.

How is Mattress Firmness Measured?

To test the level of firmness of a mattress, simply lie down on it in your favourite sleeping position and ask yourself this question:

‘Does the mattress feel ‘soft’ or ‘hard’ to me?

A ‘harder’ feeling would indicate a higher relative amount of firmness – whilst a ‘softer’ feeling would suggest a less firm mattress.

This is a really good test because it accounts for the level of firmness relative to your sleeping position, body weight, and the materials of the bed.

But what if you can’t lie on the mattress before you buy it?

If you’re looking to buy a mattress online, then you’ll have to go by numbered ratings or general wording such as ‘soft’ or ‘firm’.

Different mattress brands may have their own ratings, which can also differ from the ratings provided by various mattress review websites.

But to help simplify matters somewhat, here’s a general breakdown of how the ratings work on a scale of 1-10 and what they mean for you as a sleeper.

1-2: Extra Soft

Mattresses in the 1-2 out of 10 rating range are typically considered to have very little firmness to them.

As such, you probably won’t find many mattresses that fall into this category since the lack of surface tension may mean that you would feel too trapped in the material and be unable to move around easily.

3: Plush/Soft

The word ‘plush’ is often used to mean different things by different manufacturers.

A plush mattress may mean one that is ‘soft’ and typically has sinkage that ranges from 1.5 to 3 inches under average body weights.

In the more general sense, some brands may use the word ‘plush’ to describe an overall softer or even luxurious feel that extends beyond the top layer of the mattress and considers the feel of the mattress as a whole.

Material wise, soft mattress are usually associated with traditional deep contour memory foam and those with a deep cushion hug.

Mattresses with a soft/plush top layer are better for lighter side sleepers as to reduce the pressure points on the hips and shoulders – something that’s usually a problem if your body weight is so low that it causes you to sit on ‘top’ of the mattress rather than sinking into it.

4: Medium-Soft

Medium soft mattresses provide slightly more surface tension than the plusher mattresses.

This can be useful if you’re a medium weight side-sleeper because the extra firmness can stop you from sinking too far into the mattress.

5: Medium

Medium is the most common type of mattress firmness on the market – with a level of sinkage and hug in the 1 – 2 inches range.

The moderate amount of surface tension is suitable for most sleeping types such as side, back, and combo sleeping (changing position frequently) for people with an average body weight.

However, if you predominantly sleep on your front and you’re a bit on the heavier side, then sleeping on a medium mattress might not provide enough surface tension to support your hips and result in backache – although the underlying support layers would need to be taken into consideration too.

6: Medium-Firm

Medium-firm mattresses are probably a better option for you if you’re a back or combination sleeper that requires more surface tension to prevent you feeling like you’re sinking too far into the mattress.

Lighter front sleepers may be able to get away with a medium-firm mattress but you’ll probably find that sleeping on your side or even your back is too uncomfortable because you’ll be more ‘on’ the mattress than in it and end up feeling the pressure points more acutely.

7: Firm

With sinkage of less than 1 inch – firm mattresses typically have less contouring properties and are best suited to back and front sleepers because they will make you feel like you’re closer to the surface of the mattress and not too sunk in.

If the underlying support is also sufficient, then a firm mattress might be able to stop you from experiencing back pain when you’re on your stomach – something that’s common in this sleeping position because even the slightest misalignment of your hips can trigger back problems.

8: Extra Firm

Extra firm mattresses provide a lot of surface tension and are best suited to heavier front and back sleepers who typically sink too far into most bed types and – in the case of memory foam and hybrid mattresses – end up touching the support layers below.

Many orthopedic mattresses fall into the extra firm category and are often marketed under the premise that they can help alleviate back pain whilst sleeping.

9-10: Ultra Firm

Ultra firm mattresses would present the most amount of surface tension and are not commonly available due to low market demand.

What are the Dangers of Selecting the Wrong Firmness?

Choosing a mattress that’s too firm or too soft can result in aches and pains that could ruin your sleep.

For example, a mattress that’s too firm can result in shoulder, hip, knee, back and other joint pains – and even numbness and tingling – due to the extra surface tension causing pressure points on those areas.

Similarly a mattress that’s too soft means that you could sink too far into the materials – where you might touch the support layers below, end up with back pain, and find it difficult to move around in the bed.

I’m now going to walk you through the steps required to help guide you towards finding the most suitable mattress firmness for you.

Woman with back ache after choosing the wrong mattress firmness.

Image source: stock image used with permission.

How to Choose the Right Mattress Firmness

There’s no one firmness that’s 100% right for every type of sleeper simply because there are so many variables at play.

Meaning that one mattress that’s ideal for one person may be too soft or firm for another.

However, there are 5 general guidelines that you can follow to greatly increase the chance of selecting the right mattress firmness and finding a bed that’s comfortable for you.

Here they are in order.

1: Sleeping Position

This is big.

I’ve already discussed how different mattress firmnesses are better for certain types of sleeping positions.

But I’ll clarify them again here more concretely because the first thing you need to do is decide which type of sleeping position you adopt the most and then use this to help you find the correct level of firmness.

Back SleeperMedium

If you’re a back sleeper then you’ll probably be best suited to a medium firmness mattress.

However, if you’re on the heavier side then you might be better with a medium-firm to stop you sinking too far into the mattress.

Front Sleeper – Medium to Firm

If you sleep on your front, then you’ll want enough surface tension so that you don’t break good hip posture and end up with back ache.

Look for mattresses that are medium to firm depending on your body weight.

Side Sleeper – Medium to Soft

As a side sleeper, you’ll find that your hips and shoulders can become painful if the mattress is too firm.

Look for a medium mattress – or even a soft one if you’re on the lighter side to allow for enough contouring and pressure relief.

You might find it helpful to check out my list of the best mattresses for side sleepers to save you some time and effort.

Combo Sleeper – Medium

If you’re a combo sleeper (change positions throughout the night) then you’ll need to ensure that the bed isn’t so soft that you get stuck in the materials – something that’s common with the old types of memory foam mattresses.

Latex mattresses can also make it easier to move around.

The best place to start would be with a medium mattress and lean more towards soft or medium-firm if you’re on the lighter or heavier sides respectively.

2: Body Weight

Once you’ve decided on your sleeping position and an appropriate firmness – you’ll want to adjust for your body weight.

The general rule is that the heavier you are – the more firmness you’ll require to prevent you sinking too far into the mattress.

In terms of exact numbers, if you’re less than 130 lbs then you’ll need to increase the level of softness.

If you’re between 130 and 200 lbs then this generally corresponds to a medium or medium-firm level of firmness.

Whilst as a heavier sleeper over 200 lbs you’ll need to increase the level of firmness.

3: Adjust For Couples

So far I’ve only been considering choosing a mattress for use with a single person.

But the reality is that if you’re sleeping with a bed partner, then you could well require differing levels of firmness based on your sleeping positions and body weights.

Also, the exact pressure points may differ between men and women due to different body weight distributions – such as in the mid section.

The best thing to do is run the sleeping position and body weight tests above and see how similar you both are and look to strike a happy medium.

For example, if you’re medium weight back sleeper and your partner is a lighter weight front sleeper then a medium mattress might be just fine for both of you.

But if the disparity is too much, then you might be forced to get separate mattresses.

You may be able to get mattresses of different firmnesses that can be zipped together to function as one unit.

Alternatively, you could buy an adjustable bed base in split king and order two mattresses in different firmnesses.

4: Materials

As a general rule, you’ll find that mattress manufacturers label their mattresses as firm, medium, or soft whilst taking into account the different material types.

But it can be helpful to realise how different mattress materials can influence firmness and comfort overall.

A sub-consideration of this would be the quality of the materials on the whole – since an inferior brand could mean less support and/or firmness.

Here’s a brief overview of the different mattress types and their construction.


Innerspring mattresses can vary greatly in terms of firmness – but particularly in terms of support.

For increased support, you’ll want to look for coils with a lower ‘gauge’ (around 13) because these springs are thicker and can provide more support.

A higher coil count can increase comfort – especially if they’re ‘pocketed’ (individually wrapped) springs – because they will mould to your shape more ergonomically.

As for firmness, you’ll want to look at the material that the upholstery layer is made from – ‘pillow top’ is popular and is typically on the softer side.

Innerspring mattresses are suitable for a wide range of sleeping positions and body weights – depending on the level of underlying support.

Memory Foam

If you’re not familiar with memory foam then you’d be forgiven for thinking that such mattresses are only available in ‘soft’.

But this is not the case.

Memory foam mattresses are available from soft to firm and everything in between – as per Amrisleep’s very popular AS range.

Comfort wise, the contouring properties of memory foam make it good for pressure relief but you’ll want to make sure the foam is either ‘cooling gel’ infused or there’s some sort of airflow matrix so that you don’t ‘sleep hot’ and wake up sweating.

The good news is that most memory foam manufacturers include cooling technology in their memory foam mattresses these days.


Latex is similar to memory foam in some respects, but is typically less conforming to your body shape and generally tends to be a bit firmer.

If you’re a combo sleeper then a latex mattress might be a good choice because the ‘bouncy’ feel makes it easier to move around without getting trapped in the materials.


Hybrid mattresses consist of a comfort top layer that’s typically made of memory foam or latex and a supportive innerspring sub-layer.

The great advantage of hybrid mattresses is that you can simultaneously get superior support thanks to the innersprings whilst being able to choose from a top layer that’s soft, medium, or firm.

5: Pain

If you suffer from any aches or pains that bother you when you sleep then the first thing to do is go see your doctor to find out what the exact problem is and find the correct solution.

But if you’re suffering from chronic back pain – or some other form of ongoing discomfort – then you might also have to factor this in to your mattress buying decision.

Just keep in mind that if you’re looking to buy a mattress to help with back pain, then you’ll typically need something on the firmer side – but don’t forget to factor in the other variables listed above.

However, if you’re a side sleeper with shoulder pain then you may need a softer mattress to take the pressure away from those areas.

Just be mindful not to buy a mattress based exclusively on a pain that could disappear quickly and thus leave you with a mattress that’s the wrong level of firmness for you overall.

Conclusion: Keep It Simple

Unfortunately, finding the perfect mattress firmness isn’t an exact science because we are all unique.

And things can get a bit overwhelming if you start to overthink the process.

But to simplify things, I would start with a medium mattress and then adjust for sleeping position, body weight, pain, and sleeping with a bed partner accordingly to arrive at the best possible mattress firmness approximation.

I say this because the ‘universal’ level of firmness used by most mattress companies is in the medium range because it supposedly accounts for 80% of sleepers.

But if you’d like to see a range of mattresses that covers the major firmness spectrum to help you simplify your buying decision even more – click the button below.

And you can choose from Amerisleep’s AS range of memory foam mattresses that go from soft to firm.

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