Firm, medium or soft: Which mattress should I choose?

Sleeping on a sub-par mattress is uncomfortable and can make for a terrible night’s sleep, but worse than that, doing so can cause a string of health problems. From backache to hip pain, poor alignment and bad posture, bedding down on an old, lumpy or “just plain wrong” mattress can spell real trouble for your spinal health. So if your mattress has seen better days, it may be time to start thinking about buying a new one.

But with so many mattresses on the market, doing so can prove to be quite a headache. From orthopaedic styles to memory foam, pocket-sprung, hybrid and even cooling mattresses, it can be hard to know where to start.

At Expert Reviews we’ve tested countless mattresses for comfort, support and quality and we recommend you start by deciding: firm or soft?

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Firm versus soft mattress

Why does mattress firmness matter?

Considering how much of our lives we spend in bed, many of us don’t pay enough attention when choosing the correct level of firmness, which can cause pain, discomfort and interrupted sleep if we get it wrong.

Thomas Høegh Reisenhus, TEMPUR® sleep specialist and sleep counsellor says, “A mattress should adapt to you, distribute your weight evenly, keep your spine straight and absorb pressure to aid comfort and relieve pain. A mattress that’s too soft will cause your back or hips to slouch and your spine to fall out of alignment, while one that’s too firm will put too much pressure on your joints.”

How is mattress firmness measured?

While manufacturers sometimes use their own scale or jargon to refer to this, mattress firmness is usually measured on a scale of 1-10, as detailed below:

1 (Extra Soft) – These mattresses have a deep sinking surface and closely conform to the body

2-3 (Soft) – Soft mattresses have a sinking surface and closely conform to the body

4 (Medium Soft) – Expect some sinking and medium soft mattresses still conform to the body significantly

5 (Medium) – Medium mattresses sink much less but still conform to the body

6 (Medium Firm) – Very little sinking on the surface with some level of conforming to the body

7-8 (Firm) – Firm mattresses have almost no sinking and very little conforming

9-10 (Extra Firm) – Extra firm mattresses should have no obvious sinking or conforming

Within this classification, we can several levels together, so levels 1-3 are generally considered soft, 4-6 are medium and 7-10 are firm.

READ NEXT: Emma Original vs Simba Hybrid: Which is better?

What are the pros and cons of a soft mattress?

Soft mattresses are the least popular variety, but they’re actually ideal for side sleepers. Being so soft, they provide relatively little support – and anyone of average size and weight (and above) may find them uncomfortable to sleep on as the “deep sinking effect” could compromise spinal alignment.

Their soft layers deeply cocoon the body – which some people find comforting – but these also trap heat, so that’s something to bear in mind, too.

Soft mattresses are often expensive due to the many layers of foam and latex. Due to this, soft mattresses tend not to last as long as medium or firm mattresses as these materials can deteriorate quickly.

Due to their construction, soft mattresses can be bigger and heavier than firmer varieties, which is something to consider when turning and rotating them.

Looking for a soft mattress? We rated the Nectar Mattress four stars, with our tester praising its 90mm soft foam layer which “lets hips sink comfortably”.

What are the pros and cons of a medium mattress?

Medium mattresses are the most popular level of firmness. This means there are plenty to choose from on the market and you can expect competitive pricing. People with an average to heavy body weight will find them generally comfortable, whatever their preferred sleeping position – and they should provide an appropriate level of support with some conforming around pressure points.

The best medium mattress we’ve tested is the Simba Hybrid Pro, which we awarded our Best Buy as it delivers on all aspects for a very comfy sleep.

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What are the pros and cons of a firm mattress?

Firm mattresses are also very popular and most retailers will offer a wide range of options. These mattresses are a good choice for heavier people as their resilience provides plenty of support for the spine; front sleepers may also appreciate this level of firmness for midsection support.

Side sleepers are likely to be the least comfortable on a firm mattress, as the minimal conforming won’t relieve pressure points in the hip and shoulders.

Materials used in firmer mattresses are highly durable as well as being less expensive than those used in softer varieties, which makes them a great value option. Temperature wise, the lack of padding means there is less heat trapping so firm mattresses are naturally cooler than softer versions.

Take a look at our in-depth review of the Eve Original, a firm mattress (with a 7.5 firmness rating) which our tester Matt said “remains supportive throughout the night, even when it warms up”.

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What type of mattress is best for you?

When choosing a mattress you should always consider your build and sleeping position. Heavy people need a more supportive mattress, while front sleepers would likely be more comfortable on a softer one. We have a longer explainer on how to choose a mattress which goes into more detail regarding the available styles, but trial and error (by trying each one out) is the most effective way of finding the best mattress for your needs.

Tim Allardyce, physiotherapist and osteopath at Surrey Physio says, “Above all, the key thing you need to do is always to try a mattress out. Head to a superstore and lie on at least ten of them. Very quickly, you’ll get a good idea of what feels comfortable. Forget price, material or any other factors. The key thing that should help you decide on one is, ‘does it feel comfortable to lie on?’”.

If trying mattresses out in stores isn’t possible, be sure to choose one that comes with a trial period. Nectar, Emma, Otty and Eve all offer home trials from 100 nights up to a year so you can be sure to find the most comfortable mattress risk-free.