Is Memory Foam Density Important in a Mattress?

When shopping for a new mattress, especially a memory foam mattress, the memory foam density is an important aspect to consider when comparing and researching options. While density isn’t the only way to find the best mattress, it does affect a few important characteristics of a mattress and the owner’s potential satisfaction.

In this article, we will explain what density is, what it means, and compare the memory foam density ranges of top brands.

What is Density & What Does it Mean?

Memory foam density refers to the mass of one cubic foot of material, that is a 12-inch by 12-inch square. Usually this is given in feet (for example you may see something like 4.0 lbs or 3.5 lbs/ft³). Denser memory foams contain greater amounts of polymers and less air, thus weigh more. The measures for all layers are important to know, and any reputable manufacturer or retailer should be able to provide this information for customers. Here is a general guide for classifying memory foam density, though individual brands may categorize their beds in different ways.

Memory Foam:

• Low Density – 2.0 lbs to 3.5 lbs
• Medium Density – 3.5 to 5.0 lbs
• High Density – 5.0 lbs to 8.0 lbs

Memory Foam Density & Longevity

Density plays a role in the overall longevity of a memory foam bed. Foams that are less dense have less resistance to compression and softening with use compared to higher density foams. The weight of the core foam, or base layer, is also important because this layer serves the ‘supporting role’ in a memory foam mattress.

If the memory foam or core foam loses its ability to support the sleeper and becomes uncomfortable, the bed will need to be replaced. Beds with low memory foam density have been shown to last around 5 years, medium density around 7-8 years, and high density around 9 years, according to surveys conducted by SleepLikeTheDead.com. While lower density beds may be sold at cheaper prices, they may need replacing almost twice as often. The quality of manufacturing also affects overall durability and consistency, but density has been shown to be a significant predictor of lifespan.

Memory Foam Density & Mattress Feel/Comfort

While density does not necessarily tell you how firm a mattress is, it can affect the overall feel and comfort a person experiences. High memory foam density creates more pronounced temperature sensitive properties, which not everyone enjoys. Some people dislike the sensation of feeling surrounded or stuck as the foam softens near their body while remaining firmer elsewhere. Denser foams can also be more affected by room temperature, becoming softer in warmer rooms and firmer in cooler rooms. Lower density foams are less reactive and return to their original shape faster, but very low density foams may not provide the ‘buoyant’ support of more dense options.

Heat and odor also have some relation to density. Because more polymers (chemicals) are present, denser foams tend to present more offgassing (15% of reviewers complain of odor versus 7% with low density). And, whether due to less space for air to flow or higher conforming/viscosity, higher density beds are also more likely to trap heat (12% complain of heat versus 5% with low density). However in terms of reported comfort and pain relief, medium and higher density foams tend to come out above low density models. [Statistics based on SleepLikeTheDead.com comparisons].

Memory Foam Density Comparison

In the following table, we compared a wide range of memory foam mattress brands, from national big names to big box retailers to emerging online brands. Some brands are more forthcoming with mattress specifications than others, so for some of the brands density is estimated (noted by an *asterisk). We looked for information  on the memory foam density and cores, as well as price ranges, and owner reviews to provide a start for readers to research.

* Indicates figures based on reliable estimations since manufacturer does not disclose.

** Indicates pricing based on manufacturer’s suggest retail price for sets.

 Overview

While every brand has its own pros and cons of ownership, comparing the densities and quality can be a useful tool for discerning value when shopping.  Because brands vary significantly, it is important to be aware of specifications to see whether or not a bed will meet your needs and expectations. Memory foam density relates to both longevity and comfort factors and is thus an important part of mattress shopping, but must also be contrasted with costs, brand reputation, and your personal preferences when choosing the best model.