In the world of mattresses, foam density refers to how much weight a cubic foot of foam is carrying, and it is expressed in pounds per cubic foot (PCF). Foam density falls into three main categories: low, medium, and high. High-density foams are primarily used in mattress support cores and foundation layers.
Sleeping well is a dream for many people, and a right mattress can help make that dream come true. If you want the ultimate sleep experience, there are two main things you need to look for in a bed: that it offers proper support so that your body and spine stay aligned during the entire night, and that it provides enough comfort for ultimate relaxation and healthy sleep.
Foam is a crucial part of most mattress models. Innerspring and hybrid ones usually have comfort layers made of foam and a coil core that provide enough support for the sleeper. All foam mattresses have multiple layers that generally vary in density. The base is usually made from high-density foam to give the bed more sturdiness and the ability to carry more weight without deteriorating quickly. We can say the same thing about the perimeter of a mattress, as edge support is essential for utilizing whole sleep surface and preventing sagging.
But what is foam density, and how do we measure it? Read on to find out, while also learning how it affects the whole mattress, and how to pick the right density based on your body weight and sleep position preference.
Density, in general, represents the relationship between substance mass and volume. In the world of mattresses, it refers to how much weight a cubic foot of foam is carrying, and it is expressed in pounds per cubic foot (PCF). For example, if something weighs 80 pounds, and measures 20 cubic feet, it would mean that its density is 4 PCF, meaning that every square foot measures 4 pounds if it has a uniform consistency.
Foam density falls into three main categories: low, medium, and high. High-density foams are primarily used in mattress support cores and foundation layers. They offer enough sturdiness to hold the whole construction and all the potential sleepers that might be using the bed. Sometimes, high-density foams can be found in comfort layers, and it usually means that a mattress has a firmer feel. In contrast, low and medium density foams are mainly used in the comfort system of the bed, since using them in the support core would lead to uneven support and excessive sagging, which would have a massive impact on mattress’ durability. However, they are perfect for comfort layers. They usually offer some level of conforming, which is essential to take the pressure of critical body points and ease the pain a sleeper might be experiencing due to improper body positioning during the night.
The saying “It’s what’s inside that counts” is especially true for mattress construction. Quality materials need to be used to get increased comfort and exceptional durability, and the manufacturing process also plays a significant role in that. When we talk about foam materials, there are several different types: latex, gel-infused, and some others. But for now, we will concentrate on memory and polyurethane foam.
Polyurethane or polyfoam is a highly flexible synthetic material made from polyol and isocyanate chemicals derived from petroleum. The use of polyfoam began in the 1950s as an alternative to natural fibers like cotton and wool. It is not expensive to make, it conforms nicely, and returns to the original shape a lot quicker than natural fiber. It is also flame resistant, resilient, and it sleeps cooler than other foam types. Polyfoam is most commonly used in bases and support cores, transitional layers, and less often in top cushions.
Memory foam is probably the most famous mattress material in use. It was first developed by NASA in 1966 to decrease the levels of stress astronauts were subjected to, due to high G force. The applied pressure and body heat soften memory foam, and as a result, it conforms closely to the sleeper’s body. That is important as it takes off pressure from the shoulders, back, hips, and joints, and it prevents the development of pain in those areas. It is called memory because it “remembers” the contours of the sleeper’s body. You must have seen one of the commercials where a person would press down on this material with their hand, and it would leave the print that would stick for a few moments and then slowly disappear. Memory foam offers great comfort and is also excellent at isolating motion, which made it one of the top picks for people who share their bed with a partner. Since memory foam is too soft, it is not used in the support cores, but all the characteristics made it perfect for comfort layers.
Density is used to describe both polyurethane and memory foam, but the PCF ranges are different for them. Low-density polyfoam is considered to have less than 1.5 PCF, medium from 1.5 to 1.7 PCF, and high-density is that of 1.7 or higher PCF. When it comes to memory foam, less than 4 PCF is considered low-density, 4 to 5 PCF is medium-density, and over 5 PCF is classified as high-density memory foam.
Most mattresses are made from different materials, and products made from just one type of foam are extremely rare. Every separate layer serves a different purpose, and choosing the right mattress depends on many factors like your sleeping style, budget, as well as temperature, firmness, motion, and many other preferences.
Some manufacturers use the terms density and firmness interchangeably when describing their products, but that is not correct. While the first one is used as a measurement for weight/volume, the second term refers to how soft or firm the whole mattress feels, and how closely it conforms to sleeper’s body. Firmness is usually rated on a 1 to 10 scale, with ten being the firmest and one being the softest option. However, most of today’s models fall somewhere in the middle, from 3 to 8, and it appears that medium firmness is the option that most people prefer, and the one that comes with the most benefits.
Besides this 1 to 10 scale, firmness can also be measured in indentation load deflection (ILD). To determine ILD manufacturers would put a circular disc with 1 foot in diameter on an area of foam about 4 inches thick. Then they measure the weight that is needed to compress the foam by 25%. The results are represented by the applied pressure, so if the load were 10 pounds, the material would have ILD of 10. Most comfort layers fall somewhere between 10 and 20, while the support cores and transitional layers have higher ILD measurements.
Even though there is a difference between density and firmness, there is a correlation between them. High-density foams tend to be firmer and to conform less, while soft and medium density ones fall on the softer side of the firmness scale, and tend to contour closely. That is why they are used in the comfort systems of most mattresses.
The density of materials used in the construction of the mattress significantly impacts the overall features and performance. In this section, we review how it affects different aspects of a bed based on extensive research and numerous customer reports.
Now that we have established how foam density affects different aspects of a mattress, it is time to figure out what is the best choice for you. You need to ask yourself what qualities you must have, and what things you can compromise on. For instance, if you are a particularly hot sleeper, you wouldn’t want to get a mattress that retains a lot of heat, since you won’t be able to enjoy it, and you will find sleeping on it extremely unpleasant.
Your weight is one of the most important factors when considering what foam density to choose. Lower-density models seem to be a preferred choice of light individuals as they offer closer conforming and pressure relief. On the other hand, heavier people should go for models that are constructed from denser material, as they offer enough support and the right amount of conforming for their body type.
Another important factor to take into consideration is your sleeping position. Some people like resting on their back, some prefer sleeping on the stomach, but it turns out that most people prefer sleeping on the side. Your mattress should provide the right support for your body, and keep your back aligned through the night. Foam is excellent because it helps keep the pressure of your hips, shoulders, and back, which leads to fewer aches and pains. Back and stomach sleeping positions allow a person’s spine to align naturally, but if the surface is too soft, it can become uneven after some time. That can lead to heavier body parts sinking in, and the spine can fall out of alignment. Some manufacturers have decided to tackle that problem by providing zoned support in their products. They use higher density materials in the lumbar area, which usually sinks the most, and that adds to the durability and proper body positioning.
When we look at the sleeper’s body weight and their sleeping style, we see some general trends in preferences. On average, most people like medium density and moderate firmness levels of a mattress. It is the top pick of most average-weight individuals, although stomach sleepers may prefer a firmer surface. Lightweight back and side sleepers usually go for softer models, while people who like resting on their stomach need a little more support, so a medium would better suit them. Heavyweight individuals enjoy sleeping on firmer, high-density surfaces, although some of those who prefer sleeping on the side might like medium ones better, as they are softer, and eliminate hip and shoulder tension better.
If you are looking for a new mattress, there are many things to consider besides foam density. We have created numerous guides to make the choosing process easier, so check our guides and reviews to find the perfect sleeping product for yourself.
Dusan is a biologist, a science enthusiast and a huge nature lover. He loves to keep up to date with all the new research and write accurate science-based articles. When he’s not writing or reading, you can find him in the kitchen, trying out new delicious recipes; out in the wild, enjoying the nature or sleeping in his bed.
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