How to Understand Mattress Firmness

Updated on March 4, 2021 While all product recommendations are chosen independently, we may receive compensation for purchases made through our site. Learn more about how we make money here.


One of the first and most important criteria that people use when shopping for a mattress is firmness. Even though it’s a term you’ll find used constantly by customers, retailers, manufacturers, and reviewers, it’s rare to find a nuanced discussion of what mattress firmness is and why it really matters.

This guide seeks to change that. We’ll provide a detailed description of firmness and how it relates to numerous other important issues like comfort and support. We’ll address how firmness affects sleeping hot, sex, and motion transfer while providing tips to help you find your optimal firmness level depending on your comfort preferences, weight, and/or sleeping position. Keep reading to get the full low-down on everything you need to know to be a mattress firmness expert!

What is Firmness?

Firmness is a way of describing the feel of a mattress specifically in terms of comfort. Sleeping on concrete would be one extreme level of firmness, while an opposite extreme would be like floating on a cloud. Firmness is often said to be very subjective because what may feel comfortable to one person can be uncomfortable to someone else. For this reason, it is common to see mattresses offered in a number of different firmness levels to allow customers to find a model that will suit their preferences.

Is Firmness the Same as Support?

Firmness is not the same as support. This is an important point to emphasize. Support refers to how well a mattress promotes spinal alignment. Firmness refers to the comfort feel of the mattress and how hard or soft it is. While there can be a relationship between the two, it is helpful to think about them separately. A mattress that offers pressure point relief and keeps the spine in proper positioning is supportive regardless of how hard or soft that mattress is. While firmness can be highly subjective, support is not.

The Firmness Scale

Terms like “extra firm,” “medium-firm,” “plush,” and others are used constantly in describing different mattress models, but sometimes it can be hard to know what to make of these terms or to know how they apply when comparing mattresses produced by different companies. As a result, we often refer to the firmness scale, which is a way of rating mattress firmness from 1-10. Below you can find an overview of this scale:

  • 1 (extremely soft): maximum softness with lots of sink; this type of extra plush mattress is rare
  • 2-3 (soft): quite soft and plush with definite sink.
  • 4-6 (medium): common firmness level that offers a middle-ground with some plushness but more limited sink.
  • 7-9 (firm): much harder mattress with only limited softness and sink.
  • 10 (extremely firm): no softness, plushness or sink; this type of extra firm mattress is rare.

The Firmness Scale In-Depth

In this section, we’ll offer more detailed information about these general firmness levels including about how they can influence support and the types of sleeping positions best suited for them.

Softest (1-3)

A 1 on the firmness scale is extremely rare, but many mattresses are offered in the 2-3 range.

Support: because their softness allows them to conform closely to the body, very soft mattresses can help to relieve pressure points and keep the spine aligned. However, the flip side of this is that for many people, there is simply too much sink and contouring, and the result can be to induce an excessive curvature in the spine.

Sleeping positions: of the main sleeping positions, a very soft mattress is usually best for side sleepers. Side sleepers tend to have more pronounced pressure points at the hips and shoulders and can benefit from more cushioning at those points. For the majority of both back and stomach sleepers, the amount of sink in a very soft mattress can draw the spine out of alignment.

Medium (4-6)

Support: these medium-firm mattresses usually offer the best overall support because they have enough contouring to reduce pressure points while not permitting excessive sinking into the mattress. Spinal alignment for most people is best maintained on a mattress of this firmness.

Sleeping positions: Sleepers in all positions tend to do well with medium-firm mattresses, and these mattresses also tend to work best for combination sleepers (who sleep in multiple positions) and couples who may not sleep in the same position.

Firm (7-10)

Support: many mattresses at this firmness level can still offer sufficient support. While they don’t have the deep contouring properties of softer mattresses, there is often enough cushioning to prevent problems at pressure points.

Sleeping positions: Some side sleepers may have a hard time on these mattresses, although often there usually is sufficient pressure point relief. Some back and stomach sleepers may find that this higher firmness helps prevent their abdomen from sinking too deeply into the mattress. The mattresses at the highest range of this group, though, are rarely comfortable for sleepers in any position.

Why Does Firmness Matter?

Some people may just take it as a given that firmness is a key consideration when shopping for a mattress. But we know that our readers often want to go deeper and understand why, so let’s delve into the big reason for why firmness matters: comfort.

It’s hard to overstate the importance of comfort. An inviting, cozy mattress plays a huge role in getting a good night’s sleep. If the first thing you’re thinking about when you get into bed is how uncomfortable you are, it’s unlikely that you’re going to sleep well. Additionally, having a welcoming mattress plays a role in your broader sleep hygiene. Experts recommend developing a routine around sleep that includes a sleep environment that induces relaxation and peace of mind. Having a comfortable mattress is a big part of forming that sleep environment.

Comfort also matters because it can play a role in whether or not you wake up with aches and pains. If you spend hours every night in an uncomfortable position or trying to contort your body to get comfortable, it’s typically only a matter of time before you start feeling the effects. An uncomfortable mattress is also probably not providing you with the support you need, increasing the risk for back issues and consistent soreness in the mornings.

Finding Your Optimal Firmness Level

With that background about mattress firmness in mind, we can start to address how to determine what type of firmness level is the best fit for you. There are several different criteria or ways to approach making this determination.


The first way of selecting the firmness level for your mattress is based on your own perceptions of comfort. As we mentioned, firmness is subjective, and no one knows better than you do what kind of mattress feels good.

As a point of reference, start by thinking about your current mattress. If you know where it falls on the firmness scale, think about whether it’s right for you or whether something softer or firmer would be better. Think also about any experiences that you’ve had on other mattresses such as at hotels or when staying with friends as a guest. You don’t need to know the exact firmness of those mattresses to be able to get a sense of whether your preference runs toward soft, medium, or firm. This is especially true if you have a more extreme preference like a very plush or very hard bed.

While we provide a great deal of general guidance about the type of firmness levels that are normally best for sleepers in certain positions or weights, remember not to discount your own experience. If you know that you’ll only be comfortable on a mattress with a particular feel, go with what you know.


Mattresses respond to the weight and pressure of the body, and as a result, the weight of a sleeper can influence how a bed feels and what firmness level usually provides the most restful night’s sleep.

Sleepers who weigh less than 130 pounds should err toward a mattress near the softer end of the firmness scale. The reason for this is that a very firm mattress is unlikely to offer much give or contouring at all for a person at this weight. In order to get the benefits of pressure point relief, most lighter sleepers need a more plush mattress in the 2-5 range on the firmness scale.

Sleepers who weigh between 130 and 230 pounds normally do best with a medium-firm mattress that falls in the 4-6 range on the typical firmness scale. At this firmness level, there is enough cushioning to create a comfortable and supportive sleep surface without the risks that come from a much softer or firmer design.

Sleepers who weigh over 230 pounds should typically opt for a firmer mattress design, ranging from 6-8 on the firmness scale. Because heavier people put more pressure on the bed, the level of sink can become exaggerated on very soft mattresses. A firmer model can still give cushioning without a risk of the mattress comfort layer bottoming out and failing to offer sufficient support.

Sleeping Position

Another way that you can home in on an appropriate firmness level for your mattress is by considering your sleeping position.

Side sleepers have more exaggerated pressure points at the shoulders and hips and usually need a slightly softer mattress in order to cushion those areas and keep the spine in proper position. For most side sleepers, a soft to medium-firm mattress works best, ranging from a 3-7, with most people getting the best results in the middle of that range. More guidance for side sleepers can be found in our guide to the Best Mattresses for Side Sleepers.

Back sleepers start out in a position that tends to be good for the spine, but they do need support around the low back in order to make sure that the natural curve of the low back does not get exaggerated in any direction. For this reason, we usually advise that back sleepers select a mattress in the 4-7 range on the firmness scale. Further guidance for back sleepers can be found in our guide to the Best Mattresses for Back Sleepers.

Stomach sleepers normally should avoid mattresses with excessive sink. Because the abdomen and pelvis will usually sink more than other parts of the body, this can put the body in an unhealthy “U” shape. Most back sleepers get the most comfort and support from mattresses in the 4-7 level with a general preference toward the higher end of that range. Additional guidance for stomach sleepers can be found in our guide to the Best Mattresses for Stomach Sleepers.

Combination sleepers, or people who regularly sleep in 2 or more positions, frequently have the best results when using a medium-firm mattress in the 4-6 range. The reason for this is that a medium-firm mattress has the most flexibility and ability to provide comfort across a range of positions. More guidance for combination sleepers can be found in our guide to the Best Mattresses for Combination Sleepers.

Other Important Considerations

In addition to affecting your comfort, firmness also influences other important elements relating to the performance of your mattress, including the following:

  • Sex: mattresses that are extremely plush or extremely firm may pose barriers to frequent sexual activity. If a mattress is too soft, partners may sink into it too much, preventing movement on the bed. If it is too firm, it may be very hard to comfortably assume many sexual positions. In most cases, a medium-firm mattress is best for facilitating sex. Read more about this and find specific recommendations in our guide to the Best Mattresses for Sex.
  • Sleeping hot: too much sink or contouring can limit airflow around the body. This can cause heat to buildup in the mattress and on the skin, which is also known as “sleeping hot.” This is primarily an issue with plush mattresses and those that are made with certain materials (such as memory foam) that more closely contour to the body.
  • Motion transfer: this refers to how much movement on one side of the bed is felt on other parts of the bed. A bed that permits a lot of motion transfer may cause people who share a mattress to be awoken or disturbed by the movement of a partner. Mattress that offer more contouring to the body usually have less motion transfer as plushness and contouring can isolate motion. In addition, a very firm mattress that does not respond much to the body’s movements at all also usually will not have much motion transfer. The level of motion isolation is also directly affected by the type of material used to build the mattress.
  • Edge support: for people who regularly sit on the edge of the bed or sleep near the edge, edge support is an important consideration. Remember that most mattresses are weakest at the edge, so if a mattress is already quite plush, it is likely to offer even less support around the rim of the bed. People who prioritize edge support usually should err toward a firmer mattress overall.

Firmness FAQ

As you think about mattress firmness, you may have a whole host of questions. We’ve tried to address the most common of these in this section, but if you have a question we haven’t covered, please contact us!

What is universal comfort? Does it exist?

Universal comfort is the “one size fits all” of the mattress world. It is the idea that a mattress can be designed to be comfortable for everyone. In truth, given the subjectivity of mattress firmness and comfort preferences, there is no such thing as universal comfort. It is possible to design a mattress that will work well for a majority of people (for example, most medium-firm mattresses), but the idea of truly “universal” comfort is hyperbole at best.

Does the firmness level affect durability?

Generally not. Durability is influenced predominantly by the quality of the design, materials, and workmanship that goes into a mattress. The only way that firmness can affect durability is that some mattresses, especially firmer mattresses, may have more margin for error to lose firmness as they suffer from wear-and-tear over the years. A mattress that is already quite plush could become wholly unsupportive if its components start to wear out. But a firm or medium-firm mattress may still retain sufficient firmness for a period of time even as it loses its full original firmness.

How can I test out a mattress to see if it is the right firmness level for me?

If you are shopping for a mattress in stores, you can lie down on a mattress to see how it feels. If you do this, we recommend that you stay on the mattress for at least 10-15 minutes to truly gauge how comfortable it is for you. Also, make sure that when you test the mattress that you lie down in the sleeping position that you normally use so that you can get an accurate representation of its comfort in your specific case.

If you are shopping online, you generally are not able to see how the mattress feels before you buy it. Instead, most online retailers offer an in-home sleep trial. This means that you get to sleep on the mattress for a period of time (often 100 nights or more) with an opportunity to return the mattress for a full refund if it isn’t to your liking. For more about sleep trials, check out our guide, How to Buy A Mattress Online.

What if my partner and I have different firmness preferences?

As with most relationship issues, start with communication. You and your partner should discuss both what your ideal firmness is and what you perceive to be your acceptable range. If there is overlap, you can look for a mattress that works for you both. If your firmness needs are wholly incompatible, you can look for mattresses that are offered with split firmness levels so that each side of the mattress has a different feel.

Does firmness affect cost?

Firmness usually does not affect cost; however, there are exceptions. In order to make a mattress more firm, some mattress makers include additional layers of foam or latex, and this can increase the overall cost of the mattress. Check with any specific mattress company or retailer to find out about pricing for individual models.

Are certain mattress types more firm?

As a matter of reputation, memory foam is known for being more plush while latex and innerspring mattresses are considered to be firmer. However, this is highly dependent on the specific design of the mattress and the formulation and construction of the mattress materials. As a result, we encourage you to look at the details of any specific mattress rather than assuming that a mattress will have a particular feel because it is made of a certain material.

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

If, as you reflect on past mattresses that you’ve slept on, you really feel lost about the firmness level that you want, we suggest two key things that you can do. First, only purchase a mattress that comes with a sleep trial and a no-hassle return policy. This can give you some peace of mind that even if you buy a mattress that isn’t the right feel, you will be able to return it without penalty. Second, buy a medium-firm mattress. Since this firmness level has the widest acceptance, it is a good place to start. Feel free to contact us if you would like further guidance!

I bought a mattress that is too firm. What can I do?

If your mattress is too firm and you’re still within the timeframe of your sleep trial, return the mattress! If you don’t have that option, you might look into a mattress pad or mattress topper that would go under your sheets. Many plush mattress toppers are available that can significantly change the feel of your bed.

I bought a mattress that is too soft. What can I do?

If it’s not too late to return the mattress for a refund or exchange, do that immediately! But if you can’t return it, your best bet is to look into a mattress topper. These products go above your current mattress and under the sheet. They are made with a wide range of different materials and in many firmness levels, including some that can add firmness to your sleeping surface.