What is the best mattress firmness? How to find your ideal fit and feel

As H&G's specialist sleep writer, I'm often asked 'what is the best mattress firmness?' I rarely give two shoppers the same answer, since every sleeper needs to find their own ideal balance of comfort and support. Plus, mattress firmness is so subjective: what feels nice and supportive to you could feel hard as nails for your partner, while their plush mattress might give you a sinking feeling.

In the same way that different clothing brands use diverse sizing systems to describe the fit and feel of a product, different mattress brands use diverse descriptions for firmness. Some mattress stores rate firmness on a numerical scale of 1 to 10, where 1 is super-soft and 10 is ultra-supportive. Others talk in terms of 'Soft', 'Medium', or 'Firm' mattresses: this system might be easier to understand, but it makes it harder to compare beds across brands.

I lead a team of expert testers to find the world's best mattress. I personally pick each tester to represent a different sleep style: some run hot, while others run cool; some lie on their stomachs, while others lie on their back or sides. Since every sleeper is different, it follows that there is no universal standard for the best mattress firmness − rather, the best mattress firmness feels different for everyone.

What is the best mattress firmness?

I asked a panel of medical professionals and sleep scientists to help me outline the pros and cons of each mattress firmness rating. Together, we can teach you how to find the best mattress firmness for you. To further streamline your mattress shopping, I've combed through our back catalog of reviews to pick out a few of my favorite mattresses that suit each of the major firmness ratings.

What is the best mattress firmness?

For ease of comprehension, we'll stick to the verbal scale of mattress firmness, talking in terms of soft; medium-soft; medium; medium-firm; and firm. The firmer the mattress, the harder it feels.

A firmer mattress is not necessarily more supportive than a softer mattress. That's because support comes from the mattress core, while firmness is linked to the comfort layers towards the top of the mattress.

What is a soft mattress?

On a firmness scale of 1 to 10, a soft mattress would fall somewhere between 1 and 3. Also known as a plush mattress, a soft mattress is made from contouring materials that closely conform to the shape of your body to create a 'hugging' sensation.

• Support: it depends on your sleep position, as well as your weight. Smaller, slighter side sleepers might appreciate the pressure-relieving properties of a soft mattress, but taller, broader sleepers will sink too far, jeopardizing their spinal alignment.
• Thermoregulation: your average soft mattress is made from memory foam, which tends to trap heat. I would hesitate to recommend a soft mattress to a hot sleeper.
• Durability: soft and squishy materials tend to deteriorate faster than firm ones. This means that soft mattresses tend to have a shorter lifespan.

What is a Medium mattress?

For the purposes of this article, we'll take the 'medium' mattress rating to encompass everything from 'medium-soft' to 'medium-firm'. On a numerical firmness scale, we're looking at the range from 4 to 6.

This is the most popular mattress firmness rating. A Medium mattress is a great option for couples who share a bed, but not a sleep style. Most of the best places to buy a mattress stock medium-soft to medium-firm models, so you shouldn't struggle to find a mattress that meets your needs.

• Support: the support of a medium mattress comes more from the core than from the uppermost comfort levels, so you don't get the same sinkage as you'd get from a soft mattress. I'd recommend a Medium mattress for any sleep position.
• Thermoregulation: since a medium mattress doesn't conform so closely to the body as a soft mattress does, it's a better option for hot sleepers.
• Durability: a medium mattress is made from sturdier materials, such as high-density foam, that resist sagging. That's why a medium mattress tends to last longer than a soft mattress.

What is a Firm mattress?

A Firm mattress would fall anywhere from 7 to 10 on the firmness scale. When you lie down on a firm mattress, you'll feel that you're sitting on top of the surface, instead of sinking into softer materials.

If you appreciate enhanced support, then you should consider the best firm mattress. We've tried and tested traditional innersprings, high-tech hybrids, and nice, dense memory foam models for pressure relief without the sinking feeling.

• Support: a firm mattress would offer the best support for back and stomach sleepers. A firmer surface helps to minimize sinking in the midsection to promote proper spinal alignment. If you're a side sleeper, or you suffer from chronic pain, I'd recommend a softer surface for pressure relief.
• Thermoregulation: since firm mattresses have little to no sinkage, they're much less likely to trap heat than softer surfaces.
• Durability: to resist sagging and sinking, a firm mattress must be made from highly durable materials. With proper care, you'll get years more use out of a firm mattress than you would a soft or even a medium mattress.

How to find the best mattress firmness for you

Which mattress firmness is best for you depends on a whole host of factors, from your preferred sleep position to your body type. I asked an expert panel of medical professionals and sleep scientists to help me match up mattress firmness ratings with different sorts of sleepers.

Best mattress firmness – by sleep position

• Stomach sleepers: 'If you are a stomach sleeper, then a firm mattress can provide the extra support needed to keep the spine in as neutral a position as possible,' says Dr. Kevin Lees from The Joint Chiropractic. 'A mattress that isn't supportive, that feels too soft, can add stress to the natural curve in the lower back and add to the extension and/or rotation of the neck in a person that sleeps on their stomach.
• Back sleepers: 'If you are a back sleeper, then you will likely get the best balance of support and cushioning from a medium-firm mattress,' says Dr. Kevin. 'If the mattress is too firm, then there may be gaps in support where the mattress no longer makes contact with the entire body. This can also create pressure points and may add stress to the spine and hips of the person using the mattress.
• Side sleepers: Dr. Kevin says that 'side sleepers tend to have more pressure on their shoulders and hips. Their ideal mattress is still supportive, just with enough cushion to accommodate those areas. Typically, a side sleeper will prefer a semi-firm mattress or a firm mattress with a pillow-top.'

Best mattress firmness − by body type

• Heavier sleepers: According to Theresa Schnorbach, a leading sleep scientist for Emma Mattress, 'Heavier individuals may benefit from a firmer mattress to provide extra support and prevent sinking. This should help to maintain proper spinal alignment and alleviate pressure points.' Some mattress brands specifically design beds for plus-sized sleepers. Try the WinkBed Plus or the Saatva HD for targeted support.
• Lighter sleepers: 'Anyone who weighs under 230lbs will probably prefer a slightly softer mattress,' advises Theresa, 'though stomach sleepers will always need a firmer mattress to keep their spine aligned.'

Best mattress firmness FAQs

What mattress firmness do hotels use?

Most hotels opt for medium mattresses. That's because the hotel managers can never be sure who they're accommodating – whether it's a back, front, or side sleeper − so it's safest to take the middle road.

I've written an entire article answering the question 'what mattresses do hotels use?', showing you where to buy the plush beds from five-star hotels.

What mattress firmness is best for kids?

Younger kids, aged 3 to 7 or 8, sleep best on a medium-firm or firm mattress. Those firmness ratings offer enhanced spinal support for growing sleepers. As your kids become tweens and teens, they might appreciate the pressure-relieving properties of a medium mattress to ease their growing pains. Saatva has great guidance on choosing a mattress for your child.

Final thoughts

There are plenty of ways to make your mattress firmer without buying a brand-new bed. The easiest and most affordable upgrade is to buy the best mattress topper. One of these thick layers of foam could lend much-needed support to a soft, sagging old mattress.