Understanding Foam Densities

There are a few characteristics of foam mattresses that many tend to confuse with one another. As you shop for the best mattress for your needs, it’s important that you’re able to distinguish these differences. Otherwise, you may make a seemingly minor mistake in thinking that can significantly impact the overall comfort and satisfaction you experience with the product you decide to purchase. Today, I’m going to walk you through everything you need to understand about foam densities as you’re sure to come across these types of specs as you shop around.

A Quick Clarification

One of the most common misunderstandings when it comes to density levels is an association with firmness. What many will mistakenly take away from density specs is that higher numbers mean a firmer mattress. If you are guilty of this, you’re certainly not alone, and it’s certainly understandable where the misunderstanding comes from. What density really reveals to you is quality and durability expectations.

You can typically expect mattresses featuring higher densities to be heavier and more solid. Lower densities, on the other hand, are lighter and easier to move around. However, with higher densities, you can often expect the increase in the compression of material to provide better durability.

Now, firmness is another important factor, and, what you need to look for in your examination of this aspect is indentation load deflection, NOT density. We offer a comprehensive guide that can help you better understand ILD which is well worth checking out.

What are Foam Density Ratings?

The density of a material is defined as its mass per unit volume. In layman’s terms, this describes how tightly the matter is compacted. Discovered by Greek scientist Archimedes, it’s calculated by dividing mass by volume.

Many would tend to think that a higher density would mean the material is more compact and therefore more firm. However, this isn’t the case when dealing with foam mattresses. In the industry, foam density is measured by using a square of material measuring 12” by 12” by 12”. Let’s say a product you’re considering has a density of 4 lbs./ft³. This means that the block used for measuring weighed four pounds.

As you compare densities and weights, it’s important to understand this testing process. If you come across a product with a three lbs./ft³ density, for example, this doesn’t mean the mattress itself weighs three pounds as it’s actual weight will be much higher. While the two terms are directly related and an increase in overall weight will mean a higher density and often increased durability, density refers to the small sample size. Therefore, correlating the terms “density” and “weight” can cause some confusion as you examine specs.

Important Aspect for Those Who Carry More Weight

If you carry a lot of weight, density is a very important factor that you’ll want to carefully consider, and this is because it will impact your level of comfort and the durability of the product you choose. Pay careful attention to the top five or six inches of the mattress as this is the area that tends to break down more quickly and develops problems such as sinkage and softening.

Heavier people obviously sink into the material more deeply, and you want to find a product with a high expectation of durability. Therefore, a higher density would be more compatible with your unique needs.

 

Analyzing Densities of Various Foam Types

There are many different types of foam on the market, and you’ve likely come across quite a few of these as you’ve shopped around. Since these materials are produced using different processes, there are aspects related to density that you should be on the lookout for, and it’s worth examining them a little more closely to help guide you.

— Polyfoam

As you analyze the comfort layers on polyfoam, a good guideline is to look for one comprised of a medium density foam of at least 1.8 lbs./ft³ for one-sided products and at least 1.5 lbs./ft³ for double-sided mattresses. However, if you carry more weight, you’re going to want to keep your bare minimum at two lbs./ft³.

As with most things in life, you get what you pay for, and money can be tight. If you are working on a limited budget, polyfoam is often a good choice as it is typically the least expensive, but you may have to compromise here. If you go for a product with a density of less than 1.5 lbs./ft³, just make sure that the tradeoff on the cheaper price is worth the long-term decline in comfort you’ll be making. If the mattress is to be used sparingly, in say an RV or guest bed, then you don’t need to worry as much about density levels in a foam mattress.