Mattress Firmness Guide – All You Need to Know Before Buying a Mattress

Written by: Andjela Kastratovic
Updated: 05/11/2022

For products purchased through the links on this page and throughout the site, we may get a referral fee (with no extra cost to the buyer). Please read our full How We Rate page for more information. There you can see how we conduct research and test products, as well.

The mattress firmness, among other things, is one of the critical aspects you need to consider when deciding on which mattress to buy. This is because how firm the bed is can significantly impact the quality of your sleep. 

For example, a mattress that’s too soft can negatively affect your sleep as much as a mattress that’s too firm could. 

It’s not that hard to understand it, though! You need to know a couple of things about mattress firmness, why it’s important, the different levels, and how to pick the best one for you.  

We created this mattress firmness guide to help you find out everything you need to know about mattress firmness before buying a mattress, and hopefully, it’ll help you out. 

What Is Mattress Firmness?

Mattress firmness refers to how hard the mattress feels. That being said, whether the mattress is hard or soft is generally a subjective matter. 

Also, most mattress companies have their way of rating different levels of firmness. However, the firmness scale is usually represented by numbers on a 10 point scale. As you’ll see later in the article, we grouped firmness levels from Extra Soft beds to Extra Firm beds. 

Mattress firmness depends on construction and material. Most mattresses are created with a support core that mainly affects the support and the comfort system, usually made out of latex or memory foam, which involves the firmness level and body contouring. Thicker comfort systems make softer mattresses and provide more pressure relief.

Why Is Mattress Firmness Necessary? 

Mattress firmness is crucial because it affects the quality of your sleep, and your sleep affects your life.

The firmness level can also affect every other aspect of your mattress, like mattress support. 

Healthy spinal alignment is one of the significant impacts of firmness and support. Your hips and shoulders should be aligned. Softer beds and firm mattresses can harmfully misalign your spine.

Do mattress research to ensure your mattress will keep your spine straight.

pressure point relief and ample support

Sleeper is heavier than the mattress can support

Sleeper is ‘on’ a very firm mattress for their weight

supportive but may or may not be comfortable on some pressure points

The Definition of “One Firmness Fits All”

There is no such thing as one firmness that truly fits everyone. However, the terms “one firmness fits all” or Universal Comfort are both present in the mattress industry. 

These terms are standard but don’t represent the truth. They’re used for mattresses with a medium firmness level. Medium mattresses can also be medium-firm and medium-soft.

The reason for this is simple. The firmness level those mattresses have, between 5 and 6 on the mattress firmness scale, is preferred by almost 80% of sleepers, which is a significant majority. 

That being said, there are still plenty of people who like to sleep on lower or higher firmness levels, so when you see a mattress that says Universal Comfort, don’t go for it immediately and make sure to test it out first. Who knows? Maybe you’ll feel better on a medium-firm or softer mattress.

The Difference Between Firmness vs. Support

Most people mix up firmness and support or think it’s the same thing. Even though they can be interconnected, they’re entirely different aspects of mattresses. A firm mattress doesn’t mean it will give your body adequate support. 

The firmness represents how a mattress feels when you lie on it. Is it hard or soft?

On the other hand, support means the mattress’s capability to keep your spine aligned

That’s why there are mattresses that feel soft, but that can give you excellent support, while some firmer ones could be harmful to your spine. 

As mentioned before, mattresses are created from a support core and a comfort system. The support core is responsible for the support, while the comfort system helps define the firmness.

When shopping for a mattress, it’s essential to remember that these two aspects are separate entities.

Firmness Scale & Chart

Mattress firmness is generally represented on a scale from 1 to 10, with one being the softest and ten the firmest degree. However, as we said before, mattress firmness is entirely subjective, so creating firmness groups on the scale could differ for most people and mattress brands. Our mattress firmness ratings are split into five groups, and we’ll go into detail about each one of them.

Extra Soft (1-2)

Extra soft mattresses, which rate 1 to 2 on the mattress firmness scale, are incredibly soft. When you lie down on this type of mattress, you’ll feel like you’re sinking into it. 

Even though this may feel comfortable, too much pressure relief can affect the support, harming your spine alignment and causing back pain. This is the type of mattress you should avoid.

Additionally, thick comfort layers generally found in extra soft and soft mattresses have a shorter life span but still increase the price. 

Soft (3-4)

Soft mattresses rate from 3 to 4 on the mattress firmness scale. They’re different from the Extra soft ones because their sinkage is smaller, from 1.5 to 3 inches. This gives it variety because a soft mattress, or a plush mattress, can have pleasing sinkage or traditional deep contour. 

The comfort layer, usually made out of memory foam or latex, is thin enough not to affect the support system. The type of sleep position this mattress is best for is side sleeping because it gives good pressure relief. However, it isn’t such a good choice for back sleepers, stomach sleepers or people with a body weight of more than 130 pounds.  

Like the previous, these have shorter life spans and cost more because of the material. 

Check out our article on the best soft mattresses.

Medium (5-6)

Commonly considered the best option for most people, medium mattresses fall between 5 and 6 on the firmness scale. They’re known for a good balance between the support system and the comfort layers, which is precisely what makes them so popular. 

You won’t sink into the bed, but it’s still comfortable. They could be medium-soft and medium-firm mattresses. Medium mattresses offer an excellent base for plenty of different sleep positions, especially side sleepers and those who are very active in their sleep. Also, medium-soft or medium-firm mattresses are suitable for couples and people of all sizes because of their versatility.

Unlike a soft mattress, a medium mattress is more durable. The comfort layer is less thick and the rest of the mattress is made out of sturdier materials. However, the prices can get competitive because of the high demand. 

Firm (7-8)

Firm mattresses fall between a seven and an eight on the mattress firmness scale. Firmer mattresses tend to have almost no sinkage, and they’re a good option for people who like a medium-firm mattress. It feels like every part of your body is pushed off the bed.

A firm and a medium-firm mattress are usually created out of a thick support layer and thinner comfort layers, so they generally provide excellent support. Medium-firm mattresses are a good option for back or stomach sleepers because it keeps their spine aligned best. A firm mattress is also a suitable option for heavier people, especially those with a body weight of more than 230 pounds. 

Lastly, beds that rate higher on the firmness scale are ordinarily made out of more durable and sturdier materials. They could also be more affordable than softer options because they use less expensive materials for comfort layers. 

Extra Firm (9-10)

Extra-firm beds, just like extra soft ones, are examples of mattress firmness extremes. On the mattress firmness scale, these types get a 10. 

Also, just like Extra soft ones, Extra firm mattresses are very rare. They’re generally not comfortable to sleep on, and they can do more harm than good to most people. 

However, there are some therapeutic extra firm mattress options for those who need them, but they’re still not as common. 

This type of mattress is highly durable and probably the most affordable one. 

Which Level of Firmness Is Best According to Weight and Sleeping Position

Sleeping positionWeight
Extra softSide sleepersLight
SoftSide sleepersLight, Average
MediumSide sleepers, stomach sleepers, back sleepers, combination sleepersLight, Average, Heavy
FirmBack sleepers, stomach sleepersHeavy
Extra firmBack sleepers, stomach sleepersHeavy

How Firm Should Your Mattress Be?

Now that you know what firmness levels exist, we should look into what could affect the choice for your future mattress. 

As we mentioned before, mattress firmness is an entirely subjective matter. However, some aspects of your sleeping habits and personal health can point you to what the right level of firmness would be for you, like your preferred sleeping position. Side sleepers have different needs than back and stomach sleepers.

Sleeping Position

Some sleeping positions require different levels of mattress firmness to ensure pressure relief and good quality sleep. Your preferred sleep position should have enough support and contouring on the mattress. 

We have listed three distinct sleeping positions here – side, stomach, and back. The best option for combination sleepers would be a medium firmness level.

Stomach Sleepers

Stomach sleepers could have problems with their lower back if they don’t sleep on a good mattress. Their mattress should have the right level of support and comfort, and the perfect choice for belly sleeping is a medium mattress.

The support system is there to keep their spine well-aligned, and the comfort system should be just soft enough to provide comfort for stomach sleeping. A mattress that is too firm will let the hips, one of the pressure points, sink too much, which will lead to a bad spinal alignment. A similar thing would happen with a mattress that is too soft. 

However, as you’ll see later on, proper mattress firmness also depends on the sleeper’s weight. This is why stomach sleepers who are very light or heavy could also go for a medium soft mattress or a medium-firm one, respectfully. 

Side Sleeper

Side sleepers probably have the biggest problem with keeping their spine aligned while they’re sleeping. The support layer of their mattress should be strong enough to hold their spine in a good position, and the comfort system should be soft enough to let their shoulders and hips, the pressure points, sink into the bed. That’s why they need a softer mattress, preferably with memory foam.

The best options for side sleepers are soft mattresses and soft to medium ones. They could also go for medium-soft mattresses with zoned support. Side sleepers definitely shouldn’t go for the firmer options because they can’t keep their spine aligned, leading to hip or shoulder pain.

Back Sleeper

Back sleepers require a mattress to keep their shoulders and hips aligned. They shouldn’t be on a mattress that’s too firm or too soft because this usually leads to pain in the lower back. 

The best option for back sleepers is medium mattresses because they usually offer enough support while giving pleasing sinkage. They could also go for a medium-firm one. However, back sleepers could also go for softer or firmer mattresses, depending on their weight. Softer mattresses can negatively affect their spine alignment.

Weight and Body Types

The heavier a sleeper is, the more pressure they’ll apply on the mattress, and the support system and the comfort layers will have different effects on their body. Typically, those who weigh more need medium-firm level and more support, while those who weigh less should go for softer options. 

The three weight ranges we have here are light, average and heavy. 

Light (Under 130lbs)

Light people don’t put too much pressure on the mattress, so the best option would be to go for a soft to medium mattress. Firm mattresses would cause them pain in pressure points, like the hips and shoulders. 

Average (Between 130lbs and 230lbs)

Sleepers of the average weight need a good balance between support and comfort. While they can generally choose any mattress they feel is the best for them, a medium mattress would most likely suit the majority of them. They can either go for medium-soft mattresses or medium-firm ones.

Heavy (More Than 230lbs)

Heavier people place more pressure on the mattress, which is why they need more support and a firmer feel. The option for them would be medium to firm mattresses. Also, they should get a mattress that’s at least 10 inches thick. 

Check out our guide on the best mattresses for heavier individuals.

Health Issues 

Firmness can negatively affect health issues that the sleeper already has. That’s why we have a list of the best mattresses for back, hip and shoulder pain

Back Pain

People with back pain need adequate support for both stomach sleepers and side sleepers. The best choice for back pain would be a medium to firm mattress, depending on their sleeping position. 

Check out our guide on the best mattresses for back pain.

Hip Pain

Misalignment can lead to hip pain. Choose a bed with adequate support for your hips while maintaining sufficient pressure relief. It’s best to choose a soft mattress or a medium one. 

Check out our guide on the best mattresses for hip pain.

Shoulder Pain 

People who sleep on firmer beds, especially those on their side, tend to experience shoulder pain. The most suitable option for them is to get a softer mattress or a medium one that falls lower on the firmness scale. 

Check out our guide on the best mattresses for neck and shoulder pain.


Couples are usually looking for a comfortable mattress for both of them and soft and bouncy enough for bedtime activities. It’s best to go for a soft to medium mattress in this case. Check out our guide on the best mattresses for sex.

Tips for Choosing the Right Mattress Firmness 

Now that you know about mattress firmness and everything that can affect the sleeper, it’s time to give you some tips for determining how firm your new mattress should be. Firmness and comfort are subjective, so these are just some suggestions. 


If you sleep with a partner, you should consider their requirements and sleeping habits. In this case, it’s best to choose a new mattress with little to no motion transfer. If you don’t have split mattresses, go for a medium to firm mattress to reduce motion transfer. 

Go For Medium

If you don’t know what to do, go for medium. This is the safest option for most people, and you’ll probably like it. If you don’t, make sure the mattress company has a warranty or a risk-free trial, so you can try out the mattress and send it back if you don’t like it. 

Too Soft Is Too Bad 

Any sort of extreme is unhealthy. A mattress that’s too soft will likely give you improper support and affect your spinal alignment. Going for a firmer mattress can bypass the negative effect on your body and sleep quality. That being said, extra firm mattresses are also bad for your body. 

Firmness Doesn’t Equal Support

As we explained before, a firmness rating isn’t the same as support. These two can affect each other, and they’re definitely interconnected, but just because a mattress is an extra firm doesn’t mean it will give you additional support. Support is defined by the mattress’ capability to keep your spine correctly aligned, which is crucial for your health. 

Sleeping Position

Every person likes to sleep differently. Pay attention to the position you usually sleep in before deciding which new mattress you’d like to buy. Check our guide above to determine which level of firmness is best for you based on your sleeping position. 

Weight and Body Types

As we said before, the more someone weighs, the more pressure they put on a mattress. Consider the sleeper’s weight before buying the mattress to ensure the best sleep quality. Lighter people don’t put as much pressure on the mattress as heavier ones. Check our short guide above again to figure out the best mattress firmness for your weight. 

Combination Sleepers

Combination sleepers, move a lot in their sleep, changing positions frequently. If the mattress is too soft, it can affect their sleep and partner. Also, it isn’t an excellent option for those who sometimes like to sleep on their side if the mattress firmness level is too high. The best choice for combination sleepers is a mattress with a medium-soft feel.

You Know Best What’s Most Comfortable for Your Body

In the end, you know what feels best for you. Firmness levels are entirely subjective. While the recommendations we gave here could apply to most people, it doesn’t mean that they’re a set of rules you should abide by at any cost. 

Follow your gut and choose what feels best, whether it’s softer mattresses or ones with a higher firmness rating.

7 Signs You Need A New Mattress

Frequently Asked Questions

What’s the Best Mattress Firmness?

Although most people prefer medium-firm firmness, there’s no actual best mattress fitness. Mattresses labeled with Universal Comfort or “one mattress fits all” are medium mattresses.

How Can I Know if My Mattress Is Too Soft or Too Firm?

If your mattress is too firm, you’ll wake up exhausted or in pain. If it’s too soft, you’ll have trouble falling asleep and have lower back pain.


Too Firm:

Puts pressure on he

  • Puts pressure on heavier body parts, which will cause an unnecessary need to turn over.
  • Better for straight body shapes.
  • Shoulders and hips will curve towards each other, bending the spine.
Too Soft:
  • Spine will not be properly aligned.
  • Softer mattresses are better for those with broad shoulders or broad hips.
  • Body will sink in to a hammock position caused the spine to curve

Are Soft Mattresses Bad?

Soft beds are suitable for side sleepers, but extra soft ones aren’t good for anyone because they provide enough support. 

Does the Firmness Depend on How Big the Mattress Is?

No, the firmness doesn’t rely on the mattress size.

Final Thoughts

Finally, this is everything you should know about mattress firmness and now you can use this knowledge to buy the proper mattress for yourself. The most important thing to remember is that your personal needs and preferences will predominantly define the firmness of your future mattress, so there aren’t any general rules. Put yourself first and figure out what suits you, whether based on your sleeping position or health issues. 

We hope that this mattress firmness guide will help you find the right mattress for you!

Reviews written by:

Andjela Kastratovic - Co-editor

Anđela is a content writer by the day and an Illustrator by night. She loves anything creative, but sleep takes the cake – that’s why she enjoys writing for Anatomy of Sleep so much!

While in high school, she got accepted for her dream job – a ‘professional sleeper’. Her job was to test new mattresses from a local mattress brand and write reports on the quality of sleep. Ever since then, she’s been in love with reviewing mattresses and putting her compelling research into ultimate buyer’s guides. While not exploring the latest brands, she likes to illustrate and spend time with her dog and friends.