If you’re in the market for a new memory foam mattress, chances are you’ve seen many companies tout statistics and statements relating to the foam density of their mattresses. There’s a good reason for this: foam density is a key factor in determining quality, durability and comfort. That said, it’s not enough to simply state the density without giving context as to why it’s important.

So, why is mattress density important? How do changes in density affect quality? What foam density is right for you? We’ve got you covered. Here’s what you need to know about why mattress foam density makes a difference

why mattress foam density makes a difference

What is Foam Density and How is it Measured?

Mattress foam density is expressed in pounds and it refers to the mass of one cubic foot of a memory foam layer (i.e. a 5-pound foam mattress means that a 12”x 12”x 12” cube of the foam weighs 5 pounds). A mattress layer with a higher density will be heavier and feel more solid than a mattress with a lower density. It’s important to note that the density of a foam layer is largely unrelated to its thickness or its firmness. Density is a quality that can be most tied to durability and support.

What are the Different Densities?

Broadly speaking, memory foam mattresses come in low-density, high-density and ultra high-density designs. Here is a breakdown of some of the characteristics of each design:

Foam Density

Pounds per ft³ Characteristics

Low Density

3 lb or less

Less durable, lower price point, less support

High Density

3.5 to 5 lb

Highly durable, longer lifespan, excellent support

Ultra High Density 5 lb or higher

Very durable, high price point, longer lifespan

Low-Density Foam

Low-density foam is typically measured at 3 lb/ft³ or lower. Many mattress brands now use this level of density due to the lower price point. However, the lower density means a shorter life span, less durability and less overall support than the higher-density models. Low-density models soften much quicker, which can result in sleepers sinking through the mattresses top layer. For heavier sleepers or those who are prone to body pain, this lack of support can lead to numerous issues. While low-density foam allows for increased airflow through the material, the heightened temperature control comes at the expense of less support.

Pros:

  • Lower cost
  • Slightly better airflow & temperature control
  • Mattresses break in quickly

Cons:

  • Less durability
  • Will quickly soften leading to shorter lifespan
  • Less support
  • May not offer enough support to those in higher weight ranges

High-Density Foam

High-density foam falls within the range of 3.5 to 5 lb/ft³. These designs offer an ideal mix of durability, support and a fair price point. The higher-grade memory foam will still cradle the weight of the sleeper, but it will also work to prop up the body while keeping its integrity. These mattresses shape to the contours of the body, leading to better support in key areas such as the back, shoulders and hips. High-density foam also provides an optimal balance between adequate airflow and long-term durability.

Pros:

  • Excellent support
  • Highly durable
  • Cost-effective
  • Supports pressure points
  • Longer life span

Cons:

  • Higher price point than low-density foam
  • Less commonly available
why mattress foam density makes a difference

The Silk & Snow Mattress is Made With High-Density Memory Foam. Learn more 

Ultra High-Density

Ultra high-density foam typically falls within the range of 5 to 10 lb/ft³. While these very high densities lead to longer lifespans, they are now less commonly made by mattress manufacturers since they also come with a much higher price tag and are not ideal for those that sleep hot. Mattresses made with ultra high-density foam have traditionally provided inadequate airflow through the material and are the reason why there is a misconception that memory foam sleeps hot. Due to the lack of popularity, there has been very little innovation to this class of foam densities and many mattress manufacturers have stopped carrying them altogether.

Pros:

  • Ample support & durability
  • Supports pressure points
  • Long life span

Cons:

  • Extremely poor airflow
  • High price point
  • Lack of innovation due to unpopularity

The Distinction Between Density and Firmness

There is a misconception that there is a direct correlation between the density of a mattress and its firmness. On the contrary, it’s common to find both low-density and high-density mattresses classified as soft or firm. There is a separate measurement for determining the firmness of memory foam known as Indentation Load Deflection (ILD). ILD is the measurement of how much weight (in pounds) it takes to push a 50” inch disc into a 15″x 15″x 4” memory foam sample and make a 1-inch indentation.¹ Most memory foam mattresses come with an ILD rating between 10 lb at the soft end and 16 lb on the firm end. That said, different mattresses will feel soft or firm depending on subjective preference. In this case, the mattresses foam density matters more because of how it affects overall quality and durability.

The Density of Foam Support Layers

High-quality memory foam mattresses are manufactured with multiple layers of different foam. So far, we’ve been discussing the memory foam layer, which is the denser layer that the sleeper comes in direct contact with. However, there are also support layers that you should take into account. High-density, high-quality support layers fall within the range of 1.5 to 2.5 lb/ft³.² These layers help to cushion the high-density memory foam layers and also provide a solid foundation.

Different Densities for Different Sleepers

No two sleepers are the same and everybody has different needs and preferences to ensure quality rest. Here’s a breakdown of different types of sleepers and the foam density that should work best for them.

why mattress foam density makes a difference

Different Body Weight

Understanding your BMI (Body Mass Index) can help you make an informed decision about what mattress density will work for you. BMI is a calculation based on your height and weight and you can find it using a helpful online calculator.

Lightweight Sleepers: For those with a BMI under 20, low-density mattresses can typically work because the mattresses materials will be under less stress. That said, high-density mattresses will often provide the same comfort for lightweight sleepers and are more capable of handling lifestyle changes down the line.

Medium-weight Sleepers: For those with a BMI between 20 and 30, high-density mattresses are the best option. They provide the ideal balance between comfort, support, durability and price point.

Heavier Sleepers: For those with a BMI of 30 or above, high- to ultra high-density mattresses are the only option. These mattresses will keep their integrity over time and continue to support the contours of the body.

Side Sleepers

Side sleepers tend to dig in deeper into the mattress and for this reason, a high-density memory foam provides ideal pressure-point relief around the hips and shoulders.

Back Sleepers

Because back sleepers evenly spread their weight across the mattress, they have more flexibility in their choice of density. That said, high- to ultra high-density designs provide better long-term spinal support than low-density mattresses.

Stomach Sleepers

Stomach sleepers should be wary of low-density models, as their backs run the risk of arching inward over time due to the lack of support. To avoid issues, stomach sleepers should stick to high- to ultra high-density designs to maintain spinal integrity.

Sleepers With Chronic Pain

Those that suffer from back pain and other aches and pains should stick to high- to ultra high-density designs as they offer unparalleled support and help to maintain proper body alignment during the night.

why mattress foam density makes a difference

Those That Sleep Hot

Traditionally, many foam mattresses were designed using ultra high-density memory foams which often gives the misconception that memory foam mattresses sleep hot. Newer generations of memory foam have addressed this issue with an open cell design that improves breathability and gel or beaded gel features that help to improve heat dissipation. Ultra high-density foams are still in use by older mattress designs but have lost popularity over the years. For this reason, many of the ultra high density foams have not adopted these advancements in cooling technology.

And while low-density mattresses are the best in terms of airflow, they do so at the expense of durability and support. High-density options still encourage adequate airflow while also offering excellent support and long-term durability.

Sleepers on a Budget

While they are consistently the cheaper option upfront, low-density mattresses are not a sound investment over the long term as they have a shorter useful life and often need to be replaced much sooner. For the best mix of high-quality and affordability, high-density memory foam designs are the way to go.

Considering a Change?

The Silk + Snow Mattress is made with three layers of high-quality foam, that provide a combination of durability, support and luxurious comfort. A 1.8 lb support layer forms a stable foundation, followed by a 1.8 lb layer of transitional performance form which limits motion transfer. These two layers support a premium 4 lb layer of gel memory foam which provides the support needed to relieve pressure points while you sleep. For added convenience, the mattress cover is fully removable and washing machine ready.

 

Sources:
1. MyFoamMattress.net. “Guide to Visco Memory Foam Mattress Firmness”
http://www.myfoammattress.net/memory/ild.html

2. The Sleep Help Institute. “A Comprehensive Guide to Foam Mattresses”
https://www.sleephelp.org/types-of-foam/