The mattress firmness scale: How to find your personal Goldilocks bed

How soft do you like your mattress? If you're like me, you might prefer a medium or medium-firm feel, supportive enough to provide good spinal alignment, while still soft enough to let you snuggle in and get cozy. 

Not your style? Not a problem -- there are plenty of softer or firmer varieties out there to suit every sleeper's preference. 

This guide explores the different levels of firmness available: what each one means, how different materials and features contribute to a bed's firmness, and how to decide which level is best for you.

Read more: How to choose the best mattress size

Mattress firmness 101

The firmness of your mattress describes how hard or soft it is. Firmer mattresses tend to be more supportive, providing better spinal alignment, while softer mattresses usually offer more pressure relief and body contouring.

The way a mattress is constructed and the materials used in that construction can all be factors in the firmness level. So, in order to get an accurate idea of what mattress firmness really means for you, let's first look at how mattresses are typically designed.

Most mattresses consist of a "comfort system" layer above a supportive core layer. The comfort system, designed to alleviate pressure points (think shoulders and hips), tends to be made of memory foam, polyfoam and/or latex, while the support core often comprises less malleable and reinforcing layers of materials like steel coils, adjustable air chambers, high-density polyfoam or firm latex. Between the comfort system and support core are transition layers, which act as a cushion or buffer between the two. 

Different types of foam in the comfort layer and how thick it is can be the determining factors in how firm the mattress is. For example, a soft mattress may have a 4-inch thick layer of memory foam in the comfort layer, while a firmer variety has only 2 inches.

Denser foams can make a mattress feel firmer as well. Firmer materials are often used in the comfort layers of firmer mattresses, such as latex or denser foams. Compared to softer varieties, medium to firm beds have a certain amount of "pushback" or "bounce" when laid upon. 

The mattress firmness scale, and how much firmness you need

Most manufacturers agree upon the use of a 10-point scale to define the firmness of their mattresses -- but there's no actual rule, and some devise their own separate systems. For those that do use the 10-point scale, however, the lower end of the scale indicates softer mattresses, while higher numbers are firmer. Here's how it's broken down, in a nutshell.

Soft mattresses 

The softest mattresses are indicated by a 1, 2 or possibly 3 on the firmness scale, providing the most cushion and contouring. They're often considered extra-soft, and sometimes categorized as "plush." These mattresses allow sleepers to sink in fully, providing deep, close contouring and offering what feels like a hug. 

While soft mattresses do feel snug and cozy to some, others may find this firmness level makes them feel stuck or uncomfortable when lying in bed -- especially heavier folks or those with mobility issues. It can cause them to sink in too deeply, leading to improper spinal alignment and possible back or joint pain and stiffness over time.

Since the materials that make up plush beds are softer, they are also known to deteriorate faster. This means that extra-soft beds can be expected to last fewer years than firmer ones. Some softer varieties may also trap heat more easily as they allow foam and other contouring materials to fill in close to the body without much air flow.

Softer mattresses are usually ideal for lighter sleepers, or those weighing 130 pounds or less. This is because when lighter folks lie down, they don't sink in very much. And since they tend to stay on top of the uppermost surface of a bed, they don't generally put as much pressure on a mattress. This makes softer mattresses appealing; they can lie on them without sinking in too much -- just enough to enjoy the cushion and contouring.

A good example of this ranking on the firmness scale is the Helix Moonlight Luxe, which is rated in the 2 or 3 range. 

Medium-soft mattresses

Coming in at around the 3, 4 or 5 level on the firmness scale, medium-soft mattresses are quite popular, tending to offer plenty of cushion and contouring while simultaneously providing a healthy dose of support. 

These beds, as well as many in the 1 to 2 categories, are said to be satisfactory for a wide array of sleep positions and ideal for side sleepers (the extra cushion is good for their joints). And like softer mattresses, medium-soft mattresses are also ideal for lighter sleepers under 130 pounds.

A slower rate of deterioration may also result from the firmer, somewhat higher quality materials used in these, so they could end up with a slightly longer lifespan than the softer varieties. 

The soft side of the flippable Layla Memory Foam mattress highlights a medium-soft mattress. It's a 4 on the firmness scale. (The opposite side is a firm 7.)

Medium-firm mattresses

Mattresses on the 6, 7, and 8 levels of firmness also appeal to a broad range of sleepers. They offer a moderate amount of support, less sinkage than the lower-numbered levels, and are suitable for different body types. 

Their body-cradling qualities help alleviate pressure, and the support holds the sleeper's spinal alignment in check, alleviating back pain. Additionally, these mattresses tend to stay a bit cooler since materials hug the body less snugly, so less heat is trapped.

Average-size sleepers, or those weighing anywhere between 130 and 230 pounds, tend to especially enjoy this firmness level as well as medium-soft. 

Some mattress brands have started labelling their mattresses in this category as "universal comfort" or "universal firmness" since they're so popular with the average-size sleeper as well as a wide array of sleep positions. Universal comfort may also refer to mattresses with a 6.5 or 7 rating out of 10, which some in the mattress industry claim is the standard medium firmness rating. 

Additionally, most couples will find a medium-firm mattress works well for them, even if they're of different sleep position preferences and have vastly different body types, since it has great motion isolation (you won't feel your partner moving or getting into or out of bed). This frees couples up to look for other features they both like in a mattress, such as cooling components or other such various customizations.

The Tuft & Needle Original exemplifies the medium-firm mattress perfectly. 

Firm mattresses

Falling into the 9 to 10 range on the scale, the firmest mattresses provide the most support, the least amount of sinkage and a lot less cushion or contouring. Some find them difficult to sleep on, but back and stomach sleepers often find their supportiveness to be very comfortable. They also tend to be crafted of high-quality materials, much of it more dense than what is used in softer models, which ultimately offers a durable mattress that stands the test of time.

Heavier sleepers, or anyone weighing over 230 pounds, are likely to opt for firmer mattresses since they can provide extra sturdy support. Since heavier folks get closer to the bed's support core when they lie down, which can give the sensation of sinking in too deeply, a more supportive mattress of a medium-firm or firm variety is great for counteracting this. Firmer mattresses provide denser materials in the comfort core, preventing the sleeper from feeling unsupported or like the mattress is sagging. 

On a similar note, since firmer mattresses offer virtually no sinkage, it's ensured that the sleeper stays on top of the mattress where air flows freely and heat isn't trapped -- so these are good for hot sleepers. Also, medium-firm to firm mattresses are best for anyone suffering from back pain, as the support provided keeps the spine properly aligned during sleep. 

The Saatva Classic mattress offers three choices of firmness, including one with a ranking of 8 as its firmest option. The Plank Mattress from Brooklyn Bedding offers a choice of firmness in a flippable mattress. The ultrafirm side ranks 9 out of 10 on the firmness scale and is designed for optimal spine support.