Mattress Firmness Guide

Defining Firmness

The term firmness refers to how stiff a mattress feels when you lay down on it. How soft or firm a mattress feels is related to its comfort layer, which is located directly beneath the sleep surface. Most mattresses manufactured today have comfort layers made from polyfoam, memory foam, latex, and other materials that cushion your body.

The right level of firmness is crucial when you are selecting a new mattress. Sleeping on a mattress that feels too soft or too firm can lead to joint discomfort or back and/or shoulder pain, as well as poor heat retention during the night. Most mattress manufacturers today offer a wide range of firmness levels in their products in order to accommodate different sleepers.

The right mattress for you will ideally be firm enough to provide adequate support, but also soft enough to conform to your figure and relieve pressure points throughout the body. You can use several factors to determine the best mattress firmness level for you, including your weight, body size and preferred sleep position. You should also look at different mattress brands and models, since construction, composition and where certain models are manufactured can all affect firmness levels. It’s important to note that mattress firmness is highly subjective. A mattress that feels too firm for one person may feel too soft for another, and vice versa.

Firmness is important when choosing a mattress, but this is not the only variable you should consider. Another important factor is support, which is often confused with firmness. While firmness denotes how stiff a mattress feels, support refers to how effectively a mattress keeps your spine aligned and relieves pressure. As the name implies, the support core of a mattress determines how supportive it will feel for sleepers. Traditional innerspring mattresses have support cores insulated with steel springs or wires, while the support cores in some newer models are constructed from foam, latex or — in some cases — chambers designed to hold water or air.

Additionally, you should evaluate mattresses based on their conforming properties, or how well the mattress contours to the curves of your body and your sleep positions. A good rule of thumb when selecting the most comfortable mattress: take all three factors — firmness, support and conformability into — consideration.  

This guide will help you choose the best firmness level based on bodyweight, sleep position and other criteria. First, let’s discuss the firmness scale we use to evaluate different mattresses.

Firmness Scale

We rate mattresses on the following scale of 1 to 10:

  • 1 (very soft): The softest mattress available. The plush sleeping surface will cause deep sinking for most people.
  • 2-3 (soft): Good contouring and reasonable sinking.
  • 4-6 (medium-firm): A good balance of firmness, support and conformability.
  • 7-9 (firm): Sufficiently firm without compromising too much comfort or conformability.
  • 10 (very firm): Extremely hard with little to no padding or conformability.

Please note that both extremes (1 and 10) are fairly unusual, and most sleepers should avoid mattresses that are this soft or hard. Nearly all mattresses will register between 2 and 9.

Next, let’s take a closer look at the different firmness levels. One thing to remember: the firmness ratings we give to mattresses are based on verified customer reviews. If a mattress does not include a firmness rating, then that means we have not received enough data about that particular model.

Very Soft and Soft (1-3)

Softer mattresses ranging from 1 to 3 usually perform as follows:

  • Support: Soft mattresses can provide adequate support for some sleepers. However, individuals who require extra support — such as those who are overweight or have chronic pain issues — should look for a mattress that offers a good balance of softness and support.
  • Conforming: Conforming is where soft mattresses really excel compared to other models. Softer materials allow the mattress to contour to your figure and hug curves more easily.
  • Price: Because they often contain high-end materials like latex or memory foam, softer mattresses tend to be the most expensive models available.
  • Lifespan: Unfortunately, a softer support core means that the mattress will probably have a shorter lifespan compared to firmer models.

Medium-firm (4-6)

Medium-firm mattresses ranging from 4 to 6 usually perform as follows:

  • Support: Medium-firm mattresses typically offer adequate support without sacrificing surface comfort.
  • Conforming: Medium mattresses are typically soft enough to provide good conformability and support your curves without sinking too deeply.
  • Price: The price-point for medium-firm mattresses often falls squarely between high-priced soft mattresses and cheaper firm mattresses.
  • Lifespan: Medium-firm mattresses usually have above-average lifespans, though firm mattresses tend to last even longer.

Firm and Very Firm (7-10)

Firmer mattresses ranging from 7 to 10 usually perform as follows:

  • Support: Firm mattresses often offer the highest levels of support, and are usually the best models for heavier people and individuals with chronic pain.
  • Conforming: Firm mattresses are typically too hard to offer adequate conformability.
  • Price: Firm mattresses tend to be the least expensive models on the market.
  • Lifespan: Excellent longevity has been reported for most firm mattresses.

What Does 'Universal Comfort' Mean?

As you shop for mattresses, you may come across a term called ‘universal comfort‘, which is a term given to mattresses that some believe offer optimal comfort to the largest number of sleepers.

Medium-firm mattresses are most often associated with universal comfort. Typically, universal comfort mattresses rank between a 5 and 7 on the firmness scale. However, the term also applies to not only firmness, but also the responsiveness and conforming abilities of the comfort layer.

How to Choose Your Ideal Mattress Firmness

Now, let’s look at ways to choose the right mattress firmness level based on your weight, preferred sleep position and enjoyability of sex.

Choosing Firmness Based on Weight

Firmness Level Ideal Weight
Soft Light to average
Medium-firm Average to heavy
Firm Heavy

Use the following weight classes to help determine which firmness level is best for you (as well as your partner if you share a bed):

  • Light (130 pounds or less): Soft and medium-firm mattresses (ranging from 2 to 5) are best for light people. They may not experience much conforming on a firm mattress due to lack of compression, and essentially float on the surface without experiencing any pressure relief.
  • Average (130 to 230 pounds): Medium-firm mattresses (ranging from 4 to 6) are considered ideal for average-sized people, though some prefer how soft mattresses feel. Medium-firm mattresses are designed to offer adequate support and comfort for this weight group, although some average-sized people may choose a softer mattress if they prefer more conformability.
  • Heavy (230 pounds or more): Heavy people tend to prefer medium-firm or firm mattresses (ranging from 6 to 9). People in this weight group compress the mattress to a greater extent, and they may sink too deeply into a soft mattress as a result. Heavy people should also look for relatively thick mattresses, ideally 10 to 12 inches thick, with a support core that measures at least six inches thick.

Choosing Firmness Based on Sleep Position

Firmness Level Ideal Sleep Position
Soft Side
Medium Side, back and stomach
Firm Back

You may prefer different firmness levels depending on whether you sleep on your back, side or stomach. Use the information below to help you decide which firmness matches your weight; each diagram corresponds to the weight group directly below it.

  • Back: Medium-firm and firm mattresses (ranging from 4 to 9) are considered the best option for back sleepers, since pressure on the body is evenly distributed.

  • Side: Side sleepers tend to prefer soft to medium mattresses (ranging from 2 to 6), since these models conform to their figure more closely and help align the spine.

  • Stomach: For most stomach sleepers, medium-firm mattresses offer the most comfort. These sleepers tend to experience pain and pressure on firm mattresses, and sink too deeply into soft mattresses since their weight is distributed less evenly.

Firmness Level and Sex

Firmness Level Enjoyability of Sex
Soft Poor to fair
Medium-firm Good to excellent
Firm Fair to good

Every couple experiences sex on mattresses differently, but our findings indicate the following about soft, medium-firm and firm mattresses:

  • Soft: Softer mattresses have less responsiveness, and the sinking effect can make people feel like they are ‘fighting’ their mattress.
  • Medium-firm: These mattresses are considered the best for sex, thanks to a good balance of bounciness, comfort and noise control.
  • Firm: Less motion isolation and more bounce makes firm mattresses better for sex than soft ones, but these can also be uncomfortable and somewhat noisy.

In addition to firmness, you should also consider mattress components when judging whether or not a particular model is well-suited for sex. Innerspring mattresses, for example, tend to be noisier and bouncier. Latex and foam mattresses, on the other hand, are usually quieter but can also cause discomfort due to sinking.

Important Questions for Consumers

Here are a few questions to ask when choosing a mattress based on firmness:

  • Does support affect firmness? Not necessarily, since support and firmness are two different attributes; firmness refers to how the mattress feels, while support indicates how well it keeps your spine aligned and relieves pressure points. Lighter people often feel that softer mattresses offer better support, while heavier people tend to prefer firmer mattresses — but overall, support has little to no effect on the firmness of a mattress, or vice versa.
  • Is the mattress too soft? Soft mattresses offer the best conforming abilities, but these models are not necessarily the most comfortable. This is especially true for anyone who is heavy or average-sized.
  • Is the mattress too firm? Firm mattresses, on the other hand, offer sufficient support for heavy and average-sized people — but lighter people may not feel as comfortable, and individuals with back or shoulder pain usually do not receive adequate pressure relief. Also, be prepared for a lot of motion transfer with firm mattresses; this can lead to nighttime disruptions for couples when one person gets up or shifts positions.
  • Is a medium-firm mattress best for me? Medium-firm mattresses offer a good balance of supportive and conforming qualities, making them the best bet for most (but not all) sleepers.
  • Should I use price to evaluate firmness? Although soft, medium-firm and firm mattresses all typically fall into distinct price ranges, you should browse different brands and models in order to find a mattress with the right firmness level that also fits your budget.
  • Does lifespan matter? Soft, medium-firm and firm mattresses all carry expected lifespans — but regardless of these estimates, you should replace your mattress every seven years or less.
  • What’s the best way to test different mattresses? Visit a brick-and-mortar store and test out different mattresses to see which ones feel right with your bodyweight and sleep position. If you share a bed with someone, be sure that this person is also present to help try out different models.
  • How to I find the mattress with the best firmness level? Choosing the best mattress based on firmness level comes down to your body type/weight and preferred sleep position — as well as your budget for a new mattress.  

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