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What is memory foam density?

Learn about memory foam density and how it affects the durability and other attributes of foam mattresses.

Last update: November 4, 2016

What is memory foam?

Did you know that memory foam was originally developed by NASA in 1966? This open-celled, temperature sensitive foam has the unique capability of matching any pressure put against it, while slowly returning to its original shape when the pressure is removed. Its use eventually spread to football helmets, medical equipment, motorcycle saddles, and even bullet proof vests.

Memory foam mattresses have long been used in hospital settings for their ability to reduce pressure on patients who are immobile for long periods of time. Other medical uses include pillows, padding, and support for people with long-term pain or posture issues. Because of this material’s unique characteristics, memory foam is an ideal choice when manufacturing household mattresses.

What is memory foam density?

Open cell memory foam. Lower density foams tend to have larger cells whereas higher density foam cells will be smaller - Mdiproducts (Own work) [Public domain], via Wikimedia Commons

Memory foam density is measured as mass per unit volume. Simply put, the denser the foam, the more foam material used in a given area, and the heavier that foam is.

Due to its construction, memory foam is denser than other, standard polyurethane foam, making it more supportive and durable. Memory foam used in mattresses are typically manufactured in densities ranging anywhere from less than 1.5 lb/ft3 to 8 lb/ft3. Very high density foams range from six pounds and higher; lower density memory foams are usually categorized at three pounds or lower. It’s important to know about the effects of mattress density because it impacts the longevity, durability, and support of your mattress. Most memory foam has the same chemical make-up, but a high density mattress will have a much better longevity. The longevity is an attribute of a mattresses firmness, however; density is not to be confused with the firmness (or “feel”) of a mattress.

Does density affect firmness?

Just because a mattress is manufactured at high density does not necessarily mean it will feel firm. Conversely, a low density mattress will not always feel soft.

Comfort levels of mattresses are measured by a foam’s indentation force deflection (IFD) rating. It's also commonly referred to as an indentation load deflection (ILD) rating. This indentation factor calculates the force required to make a 1 inch dent into a 50 square inch section of memory foam; the more force required, the higher the IFD rating. Most mattress comfort layers range from 3 to 5 lb/ft3 but can have vast differences in firmness because of their IFD rating. Basically, while a foam's density can affect firmness up to a point, a mattress’ firmness is influenced more by the foam's IFD and mattress layer composition. Being able to offer different IDF ratings combined with high-density foam, you can have diverse, distinct firmness levels with the consistent quality that high density foam offers.

What else does density affect?

Durability

As a general rule, low density foam is less durable than high density foam as a lower concentration of foam material breaks down quicker from repetitive, nightly wear and tear. With proper care, a high density foam mattress can last you decades. In fact, a high density mattress can last as much as 50% longer than some of the lower density mattresses you can commonly find online. Regardless of what firmness you prefer, your Novosbed can last for years because every mattress is constructed with premium quality, high density foam.

Sleep quality

A lot of people wake-up with aches and pains and don’t realize that their mattress might be the cause. Mattresses with high density composition are favoured by people with body aches and pains as it improves circulation and relieves stress on pressure points by helping to evenly distribute a person’s body weight. This has revolutionized beds in hospitals and extended care facilities, helping to reduce the likelihood of skin and body tissue issues associated with prolonged time in bed.

Foam response time

Foam response time is the amount of time required for a foam to return to its original shape upon being compressed and released. Lower density foams often respond faster because there are larger air pockets in the foam to help spring the foam back quicker. Higher density foams tend to respond slower. A faster responding foam is easier to move on and get up off, but it may not offer as much contouring support as a higher density foam would.

Price

Naturally, as the amount of material used in manufacturing increases, so does the price. Because of this, lower density mattresses tend to cost less as less foam material goes into the mattress. Even though a cheaper price might sound enticing, density is an important factor to take into consideration as it also affects the durability of your mattress.

Contouring & Temperature Sensitivity

With memory foam, you get to enjoy a level of “temperature sensitivity”. Many new memory foam owners find the feeling strange at first, but soon enjoy the sensation since the reaction is a gradual response to your own, specific body temperature. This “hug” is one of memory foam’s more desirable traits, as the end result is an even, full-body, supported sleep. Upon contact with your body heat, the memory foam responds and begins to contour around you while the foam surrounding you stays firm.

The density of the foam plays a part in the amount of contouring you will receive as the amount of contouring rises as foam density increases. Because of memory foam’s temperature sensitivity, these mattresses have had a reputation for sleeping warm, but this is no longer an issue with modern mattress design improvements.

Weight

Unsurprisingly, density also affects weight. The denser an object is, the heavier it will be. A dense mattress will provide a solid, supportive sleep, so make sure to look for a total mattress that has some weight to it. Of course, there is no ideal weight since a mattress’ weight will vary depending on the type and size of the mattress (that is, obviously a twin sized mattress will weight much less than a king sized mattress). As a rule of thumb, a queen size, 11" tall, high-density memory foam mattress should weigh around 90 lbs.

Weight can also be a problem as getting a mattress from a store to your front door can be quite difficult, especially with smaller vehicles. Of course, this is usually only half the battle; stairs, doorways, and tight corners can be a nightmare to navigate a large, heavy mattress. In fact, those who are purchasing an ultra-supportive mattress may already have back or posture issues that prevent any heavy lifting at all. Because Novosbed ships in a compact box—no more pivoting is required. The “getting-it-home” nightmare is taken care of with fast door to door delivery. Additionally, Novosbed offers a white glove service that includes delivery, setup, and, for an additional fee, removal of your old mattress.

Memory foam handprint The handprint demonstration is a good way to see memory foam's unique response time properties - Johan (Own work) [CC-BY-SA-3.0], via Wikimedia Commons

How do the different densities compare?

Low and high densities both have advantages and drawbacks. But depending on your sleep preference, a certain level of density might work better for you.

Density comparison

Density Price Durability Break-in Foam Response Increased Pain Relief
Low Density Shorter Faster
High Density Longer Slower

Popular brands that use high density memory foam

Numerous brands utilize memory foam in their mattresses, but the number of models offered, density used, and firmness options differ greatly.

Brand comparison

Brand Owner Satisfaction* Number of Models Memory foam thickness Memory foam density (lbs/ft3) Firmness
Casper 78% 1 1.5 4 Medium
Dreamfoam 81% 1 5 4,5 Med-soft
Loom & Leaf 82% 2 4.5 4,5 Med-firm or firm
Novosbed 84% 3 4-5 3.7-5 Soft - med - firm
Tempur-Pedic 81% 14 3 - 7.2 Unknown x-soft - x-firm
* Ratings via Sleep Like the Dead

Conclusion

Here are some important points to remember about density when purchasing a memory foam mattress:

  • Memory foam is denser and more durable than other foams used in the manufacturing of mattresses.
  • Density is a measurement of mass per unit volume (often given in lbs/in3); the denser the foam, the more material used in a given area.
  • While foam density affects the weight, durability, price, and lifespan of a mattress, it does not necessarily reflect the firmness or “feel” of a mattress.
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