A Buyer’s Guide to the Mattress Firmness Scale

If this is your first time buying a mattress, you may not be familiar with the many terms used to describe them. After all, there are modern mattresses made of everything from space-age gels to latex to camel hair. Some mattresses have innersprings, others are entirely foam, and many are hybrids—and all of these factors affect how firm or soft your mattress will be.

Understanding just what your mattress is made of, and how it is constructed, is key to finding the best fit for you. That means tracking down the mattress with just the right amount of firmness and support for your body type, durability needs, and preferred sleeping position.

Mattress Metrics

Softness or Firmness

The quality of your night’s sleep is heavily dependent on how much support you’re getting from your mattress, and one of the major factors in the quality of that support is the firmness scale. This numerical scale attempts to quantify comfort by describing how soft or firm a mattress is, on a scale from one to ten. It’s not an exact science—a mattress that feels downright plush to you may be firm-hard to someone else. The numerical scale of firmness, however, will let you know what to expect when you lie down on a mattress.

Mattress Support

The support layers in a mattress tend to be toward the bottom, while the comfort layers are on the top, nearest to the body. The strength and quality of these base layers dictate how much the bed will sag and sink over time, in addition to how noisy it will be, and how quickly it absorbs and holds body heat.

The main support layer is usually the thickest part of the mattress and holds metal springs, high-density foam, latex, or air chambers. It may be a hybrid of these materials, and sometimes the whole layer is encased in high-density foam, or an additional base layer is added, for additional support. What materials are chosen for these layers are dependent on whether a mattress is meant to be on the softer or firmer end of the scale.

  • Soft- In general, a soft mattress is one that you sink in to rather than lie on top of. That’s because it’s constructed from various cushioning materials to be particularly plush. Memory foam mattresses, with their body-contouring and pressure relieving abilities, often belong in this category. For this reason, they tend to be preferred by those who sleep on their side.
  • Firm- Firmer mattresses go easy on the cushioning and utilize springs or high-density poly foam. When you push down on a firm mattress, you’ll feel yourself being pushed right back. Those with joint pain and those who like extra support often favor firm mattresses.

Ultimately, firm and soft mattresses have two different missions. Softness is all about comfort, while firmness is about bodily alignment.

Pain Points and Pressure Relief

A mattress with the right level of firmness for you will be comfortable and supportive enough that you’ll notice the difference. Effective support ensures that your weight is evenly distributed across the bed, and that your spine is aligned. The result is reduced pressure, which means waking up feeling refreshed instead of sore.

You will also feel the effects if your mattress is wrong for you. Too soft, and your spine can be misaligned, leading to hip and back pain. Too firm, and the heavier pressure points of your body will go unsupported.

Certain sleeping positions aggravate certain pressure points. Side sleepers, for instance, are more likely to feel pain in the hip and shoulder areas, because these regions are taking most of the weight. Back sleepers often deal with lower back pain. Softer layers of cushion toward the surface of the mattress, such as latex or memory foam, help relieve pressure. On the body. A mattress topper can also help.

Your body shape can also dictate whether a soft or firm mattress is better for you. Side sleepers with wider hips are better off with softer mattresses, say researchers at America’s Cleveland Clinic, so they can sink into the mattress and receive even support. Those with narrower hips that are more “straight up and down” will be better supported by a more rigid surface, because of the increased pelvis and lower spine support. Stomach sleepers will find that a mid-range, which can accommodate the body weight being placed on their bellies while still supporting their spines, is the best option. Back sleepers can afford to be less choosy, and will fare well on mattresses anywhere from medium-soft to firm.

Mattresses that relieve pressure are particularly important for those who spend longer periods of time in bed, such as those disabled and chronically-ill people.

How to Shop Using the Mattress Firmness Scale

Your sleeping position, how much support you’ll need for your pressure points, your body shape, your weight, your level of mobility, and more, all come into play when deciding how firm your mattress should be. It’s not just a case of typing into Google ‘what’s the best mattress for back pain?” This is especially true because the firmness scale is not standardized—much like clothing sizes, the meanings behind the numbers can vary greatly depending on the manufacturer.

Doing your research is worthwhile though. High-quality mattresses are made to last, so the right choice now will mean increased comfort for years to come.

Every Level on the Scale

The following scale is relatively standard across most popular mattress brands. It’s also subjective, and far from universal, so be sure to take these ratings with a grain of salt, and always test out a mattress yourself before you commit.

Graphic showing a soft, medium, and firm mattress

Plush and Soft Mattresses

  • 1-2: Extra Soft- For the majority of people, a mattress this soft isn’t even worth looking at. A one or two on the scale provides very little support—practically like sleeping in quicksand. It leaves your spine floundering for alignment. This grading is best avoided.
  • 3-4: Soft– If you’re looking for the best soft mattress for side sleepers, this range is for you. These mattresses just shy of the halfway point on the scale offer a cushioning softness, but they also provide some support for the back, and can effectively distribute weight. If you’re a back or stomach-sleeper, however, this mattress is likely to be too soft for you. You’ll definitely be “in” a three or four, rather than “on” it.

Medium Mattresses

  • 5: Medium Soft– This is the most popular grade of mattress firmness. Its average firmness is well-suited to a variety of sleeping positions, as well as those who weigh around 200 pounds.
  • 6: Medium Firm– A back sleeper will be better suited to a medium-firm mattress. The support system in this type of mattress will involve pocketed coils or high-density poly foam. A six will still have more mobility than a higher-grade mattress, and so it will prove more comfortable. This type of mattress also suits someone who sleeps on their stomach, thanks to the fact it will be firm enough to distribute the body’s weight, ensuring the spine won’t curve.

Hard and Firm Mattresses

  • 7-8: Firm– To find the best firm mattress for an individual who is seeking relief back pain, or who weighs more than 200 pounds and sleeps on their back or stomach, you would look in this grading range. There is comparatively less cushioning, and you can be sure your spine will be well-aligned.
  • 9-10: Extra-Firm– These mattresses are a good option for those with less mobility who spend more time in bed, as the level of support helps to avoid injuries from prolonged pressure.

Getting the Mattress Metrics Right

In order to reap the full benefits of a good night’s sleep, from improved mood to a stronger immune system, you need to find the right mattress. This involves considering what temperature you like to be while sleeping, whether your allergies might be exacerbated by certain materials, whether you have any monkeys jumping on your bed, and a range of other factors.

The technologies and terms on the market today can be dazzling and even overwhelming. Starting with the firmness scale will help give you a solid basis for figuring out what you need.