When Goldilocks wanted to sleep in the Three Bears’ house, there were three beds to choose from, each with a different firmness. To find the best bed, she tried them all. Papa Bear’s bed was too hard, and Mama Bear’s bed too soft, but Baby Bear’s bed was just right.
When it comes to choosing a mattress, the desired level of firmness is a matter of personal preference. Fortunately, mattress shoppers can select from a mattress firmness scale with several different levels of firmness:
The Mattress Firmness Scale
- Extra Soft
- Extra Firm
Choosing a good mattress is a very personal choice. Firmness is partly objective and partly subjective, as you can see in almost any mattress review. The same mattress may feel firmer to one person and softer to another, a factor which bears on customers’ mattress ratings.
What to Consider When Picking Mattress Firmness
There are several factors to take into account when choosing a mattress with the right firmness. These include materials, weight, body size and shape, health conditions, and partner sleeping.
There are several mattress types available which are made using a variety of materials. These materials can interact with your body in different ways. Depending on the type of mattress you choose, your preferred level of mattress firmness can change.
Memory foam was developed from the material NASA commissioned to cushion astronauts on lift-off. Memory foam is heat sensitive and it softens when it warms up. With memory foam, a sleeper’s body temperature can affect the firmness. The density of the memory foam also comes into play. Denser memory foam is firmer when it is cold but softens more when warm — this is what makes it so conforming.
Lighter memory foam, on the other hand, is not as firm when cold, but is also less heat sensitive. When it warms up, light memory foam doesn’t soften up as much as denser memory foam. This means that the firmness of a memory foam mattress can vary widely between brands. And a mattress can change firmness during the night as the bed becomes warmer. If you are considering a memory foam mattress, be aware that the level of firmness is hard to predict and will fluctuate during the night.
Hyper-Elastic Polymer™ Material
In contrast, the Purple® Mattress has a Hyper-Elastic Polymer™ material in the Purple Grid™ which does not retain heat. A Purple® Mattress has the same firmness when you wake up in the morning as it did when you went to bed.
Gel Memory Foam
Some manufacturers add gel to memory foam. The gel can help enhance support, but it is primarily used to cool the foam by absorbing and transferring heat. However, be aware that even gel-infused memory foam will heat up during the night.
Latex mattresses were invented in the 1920s but did not become popular until after the introduction of memory foam mattresses in 1991. Latex foam is resilient. This means that the more your body weight pushes it down, the more it pushes back. Therefore, latex feels soft at first, then firmer as you go down until a balance is reached. Latex foam can be made softer or firmer in the foaming process. There are two primary processes for making latex foam. Dunlap latex is denser and firmer at the bottom, but less dense and softer at the top (unless flipped over). Talalay latex has the same density all the way through the mattress.
The original support for modern mattresses was an array of steel coil springs known as innerspring. These coils were actually developed from springs in buggy seats. By World War II, almost all mattresses made and sold commercially were innerspring mattresses. There was little padding — typically just some cotton batting — so the firmness depended entirely on the coils.
The original springs were Bonnell coils, followed by pocket coils, offset coils, and continuous coils. Most of these coils are on the firm side. Continuous coils are generally the firmest, but extremely firm Bonnell coils are used for extra heavy people.
Today, pocket coils are the most popular type of innerspring, mostly because of their conformity and ability to minimize motion transfer. They are also the coils which do best for compressing and rolling a boxed bed. Hybrid mattresses, such as the New Purple® Mattress, use pocket coils and are quite popular these days.
Where do hybrid mattresses sit on the firmness scale?
Hybrid mattresses essentially replace the foam support core with pocketed coils. Mechanically, it may be the same firmness, but for a sleeper, this could feel a bit softer since the pocket coils are more conforming than a very firm foam slab.
Micro coils — including nano coils — are sometimes used inside innerspring mattresses. These are extremely short pocket coils. An array of micro-coils is made as a sheet (the fabric pockets adhere to each other). This sheet of tiny coils can be inserted between two foam layers to adjust the firmness of the mattress. The actual effectiveness in moderating firmness is debatable, but they do seem to help keep a mattress cooler.
A pillow top mattress is not really a unique material, but rather an added section of a mattress. A pillow top mattress has a padded cover sewn to the top of the mattress to serve as a comfort layer. Most pillow tops are 1” to 1.5” high, though some are 2” or more. The materials in a pillow top can be made with fibers, poly foam, or memory foam.
A pillow top will make a mattress softer. The way the pillow top is attached to the mattress can affect how the mattress feels. The bottom cover of a traditional pillow top is sewn to the top panel of the mattress cover, and it is single edged like a true pillow. This makes it feel softer at the edges.
As a general rule, a heavier person needs a firmer mattress, while a lighter person will typically prefer a softer mattress. You need enough support to align your spine properly, and if you are too heavy for the mattress, it will sag. And if you are too light, you may not sink in enough for real pressure relief. Use the mattress firmness scale guide in this article to indicate the range of firmness appropriate for you. Your best mattress should be within this suggested range.
Body Size and Shape
Body type is an important factor when determining the firmness of a mattress. Some people are tall and lanky, while others are short and stocky. A compact body puts more concentrated pressure on a mattress. For example, press on your mattress with an open hand, then with a closed fist. Which sinks in more? This is why a stocky sleeper may need a slightly softer mattress to lessen pressure than a lanky sleeper with long arms and legs.
Interestingly, your sleeping position can also affect the firmness of a mattress. A sleeper is more likely to float on top of the mattress when sleeping with their arms and legs spread out, as opposed to sleeping curled up in a fetal position. Sleeping in a ball on a firmer mattress puts more pressure on protruding joints. If you or your partner tends to curl up at night, pick a mattress at the lower end of your firmness range.
There are three basic sleeping positions: back sleeping, stomach sleeping, and side sleeping (the fetal position is a variation of side sleeping). Each sleep position can affect the preferred level of firmness in order to promote proper spinal alignment.
The best sleeping positions are largely determined by health conditions and other factors. Side sleeping is better for sleepers with breathing problems, such as sleep apnea or asthma. Back sleeping is recommended for those who have had hip surgery, back surgery, or have scoliosis. The one significant benefit of stomach sleeping is the avoidance of snoring and sleep apnea, though you need proper support to avoid back and neck problems.
Sleeping on your back is known as the supine position. It is a natural position for the spine, but a certain amount of firmness is still needed to keep the lumbar from sagging. Typically, the recommended firmness for back sleepers is medium to medium firm (4-7). Even then, some back sleepers may need additional lumbar support, and it’s a good idea to lift the knees slightly with a pillow. Adjustable foundations, such as the Purple PowerBase, are better for back sleepers than for other sleep positions, especially if paired with a good mattress.
More people sleep on their sides than on their backs or stomachs. A side sleeper needs to have the shoulders and hips sink into the mattress. This reduces pressure on the joints, and it allows the spine to be laterally straight. For these reasons, a side sleeper should consider a mattress at the softer end of the preferred firmness range (4-5 for most).
Stomach sleeping is not as popular as side sleeping or back sleeping. These sleepers should choose a mattress on the firmer end of the preferred range (6.5-7). Even then, the pillows used by a stomach sleeper are very important. Many stomach sleepers use body pillows because they can help support the spine.
Some health conditions necessitate having a softer or firmer mattress. For instance, some mattresses are designed with a combination of softness and supportive resilience for fibromyalgia, while other mattresses are developed to help acid reflux sufferers. Firmer mattresses are typically prescribed for people with back pain. However, the phrase, “The firmer, the better” is now shown to be an extreme view, since what is needed is underlying support with a softer surface. Many customers base their mattress ratings on how well the mattress relates to their specific health conditions.
Sleep apnea is usually addressed either by an elevated upper body (with a wedge or an adjustable base) or by side sleeping, and side sleeping requires a softer mattress. If a person can’t breathe unless sleeping on their stomach, then they need a firmer mattress and added support for the belly/lumbar.
Sciatic nerve pain requires a softer mattress for less pressure on the nerve. Sufferers of sciatica are also often advised to sleep on the side opposite of the side with the pain, again calling for a softer mattress.
People suffering from a curvature of the spine should sleep in the supine position. The mattress should be medium firm to firm, since sagging will make the problem worse.
If you share a bed with someone else, chances are that each of you prefers a different level of firmness. According to mattress reviews, the best mattress for couples is typically a king mattress which can adapt itself to each of you.
The best solution is a medium-firm mattress with a softer top layer over a supportive and resilient layer, such as the Original Purple® Bed or the New Purple® Mattress. You can also put two twin XL mattresses side by side to make a king bed. This way, one mattress could be quite soft while the other is extra firm.
The Mattress Firmness Scale
The mattress firmness scale defines how firm or soft a mattress feels, both for the comfort layer and for overall mattress support. This is done in two ways. One method uses descriptive words for each level of firmness. The other way is to assign a numeric value (usually 1 to 10), which may be refined to include decimal numbers (such as 4.5 and 6.7) or fractional numbers (5½, 6½).
Not everyone is consistent in how they describe mattress firmness. Sometimes, the words “plush” or “immersive” is used to describe the softness of a mattress. On the other end of the scale, most brands use the term “firm mattress,” although some people may say “hard mattress.”
The Numeric Firmness Scale
When choosing a mattress, it’s important to know what the description means if it has a numeric firmness rating. Manufacturers, retailers, and reviewers often assign a number on a 10-point scale to rate the firmness of a mattress. Most websites, including Consumer Reports, assign a 10 to the firmest mattresses. However, a few brands use 10 for the softest mattresses, and 1 for the firmest. Admittedly, this can certainly be confusing! Is anyone for standardization?
How Is Mattress Firmness Measured?
The firmness of a mattress can actually be measured scientifically. A standardized weight with a defined surface area is pressed into the mattress. This can be an object with a standard shape, such as a ball or a cube, or it could be a plate mounted to a mechanical arm. The amount of sinkage (how far it goes into the mattress) is measured for each weight and amount of pressure. This is how many mattress companies rate the firmness of their mattresses.
A mattress is considered soft (plush) if it sinks in between 1.5 and 3 inches. If the sinkage is just an inch, it is medium. If there is little sinkage, it is firm. A mattress is labeled as extra firm if there is no sinkage at all.
However, for human sleepers, there is more involved than simple mechanical firmness. Also, the effective firmness of a mattress — how it feels to you — depends on the mattress type. This is why there is always a variance in how firm a mattress is to the user. Keep this in mind as we discuss the firmness levels.
Let’s talk about the seven firmness levels: Extra Soft, Soft, Medium, Medium-Firm, Firm, Extra Firm, and Universal.
Extra Soft: 1-2
These are the softest mattresses. Extra Soft is rated 1-2 on the numeric scale. It’s extremely rare to sleep on a mattress rated at 1.0 because it has practically zero support. Most extra soft mattresses are rated at 2 and are generally quite deep. They are very soft at the top with many layers beneath. The layers become firmer as they go down. This is the only way an extra soft mattress can have adequate support.
Extra soft mattresses are sometimes considered luxury mattresses because you can sink in deeply and still find support and comfort. The extra layers make the mattress very expensive and very heavy and may be too high off the ground for many sleepers. Believe it or not, some companies sell bedroom steps made for getting in and out of very high luxury beds.
A soft mattress is usually rated 3-4. This is a bit too soft for average-size sleepers, and especially for heavier sleepers because they sink in too much. Very lightweight (110 lbs. or less) and lightweight adults may sleep well on a soft mattress. The best position for a soft mattress is side sleeping because it allows the shoulders to sink in, relieving pressure on the joints. A lightweight side-sleeper can still have proper spinal support, but heavier side-sleepers need more lumbar support.
The best soft mattress is typically rated at 4 since it provides a little more support. This is especially true if there is a transitional layer from the soft top layer to the base. This keeps the softness of the top while providing needed support. The Purple® 4 is considered by many to be the best plush mattress, because of the underlying conforming support. Some call it the best mattress for side sleepers.
Small children still using crib or toddler size mattresses can be adequately supported by a soft mattress rated 3 because they are extremely lightweight and don’t sink in very much.
The average numeric rating for Medium is 4-5. This is in the middle range, which is the firmness preferred by many. In fact, most mattresses sold are either Medium or Medium Firm.
A medium mattress is a good choice for average-size side sleepers and back sleepers. Stomach sleepers do better with Medium Firm or Firm because more mattress support is needed to keep the spine from sagging.
Innerspring mattresses with four inches of latex foam or memory foam comfort layers are usually rated as Medium. With about three inches of foam, they may be rated as Medium Firm. Of course, this depends on the firmness of both the coils and the foam.
The Purple® 3 is a top medium-firm mattress.
Medium Firm (6 to 7) is, for most people, the firmness level of the most comfortable mattress. While it’s not suitable for everyone, it does suit the largest number of people. This firmness is right for all sleeping positions of average-sized sleepers, and acceptable for lightweight and light heavyweight sleepers.
The best medium-firm mattress has enough softness on top to ease pressure on larger body parts, such as shoulders and hips, and enough support for the head, spine, and feet. This is especially important for side sleepers since more people sleep on their sides than on their backs or stomachs.
A Medium Firm mattress has layered support: a softer top layer, a firmer transition layer of high-density foam, and an extra firm base. This graduated support is in the Original Purple® Bed. The New Purple® Mattress (Purple 2, Purple 3, and Purple 4) does this with its pocketed coil support core. The Purple® 2 is Medium Firm or Firm, but with a soft touch on top.
Firm mattresses are rated between 7-8 on the scale. Some people — especially heavier people —