The Complete Guide to Understanding Mattress Foam Densities
Not all foam mattresses are made the same. One of the ways foam mattresses can differ from each other is through their foam densities.
Understanding foam densities is an important step in determining the right style of foam mattress for your sleep style. And will help you out in your mattress purchase process!!
Foam mattress density can affect various aspects of sleep including:
- spine support
- comfort level
- temperature regulation
- motion disturbance
- noise disturbance
- pain relief
Additionally, the density and manufacturing process can also determine factors like price, odor release, toxicity, durability, and mattress weight.
What is Mattress Foam Density?
In this case, foam density is specifically the measurement of weight for one cubic feet of foam. To determine the density, the total weight is divided by the total volume.
Foam densities are typically measured in pounds per cubic feet.
In general, there are three levels of mattress density. Foam mattresses are manufactured to fit into one of these three levels of density: high, medium, or low.
Each type of foam material has its own range of values for each density level. For example, a low density memory foam mattress will having a density of less than 4 lbs./ft³. A polyfoam mattress at the same level will have a density of less than 1.5 lbs./ft³.
A simple way to think of foam density is the denser the foam, the more durable it is (although manufacturing quality also plays a significant role in durability). As we’ll explain later, a dense material can also be very soft, so don’t confuse density with firmness!
Different Types of Foam Mattresses
In understanding foam mattress densities, it is important to note that there are a variety of foam mattresses that each offer unique features and density levels. Let’s explore them now.
1. Memory Foam Mattress
Memory foam is a type of polyurethane foam that is denser and more viscous. It contains the same raw materials and is made using a similar manufacturing process.
What makes memory foam unique is the additional chemicals that are used in the final stages of the manufacturing process. This step is what creates the “memory” effect that memory foam is named for.
Memory foam products are also commonly referred to as “tempurpedic” products because of how popular the Tempur-pedic brand of memory foam mattress have been over the last 20 years.
The downside to memory foam is its weight, and the sinking or trapped feeling that the memory foam often has, also leading to common complaints of sleeping hot as the body sinks in and creates a heat sink.
2. Polyurethane Foam Mattress
Polyurethane foam (also known as polyfoam) is made by combining polyol and diisocyanate.
It is very similar in structure to memory foam though it has a lighter density which means the mattress is significantly lighter.
Polyfoam can be constructed in a variety of firmnesses and rebound levels which can be designed to give a mattress that is supportive while avoiding the downsides of the slow rebound and sinking feeling of memory foam. Polyurethane is also hypoallergenic and very durable, and can be manufactured with an ‘open cell’ structure that allows airflow to promote cooling.
The 2920 Sleep mattress is made from 4 layers of polyfoam, each layer with different density to provide a supportive yet very comfortable feeling. The top layer in particular uses a new generation (and expensive) open-cell poly foam that is very comfortable and very breathable to avoid overheating while sleeping.
3. Latex Foam Mattress
Latex foam is a popular alternative to polyfoam and is crafted from synthetic or natural latex that is derived from rubber trees. Organic or natural latex foam is a more costly option compared to synthetic latex foams.
Latex mattresses tend to be very heavy, and have a unique “springy” characteristic that may be difficult to get used to. Because of this, the design of the mattress becomes very important to ensure the right blend of support, comfort, and without too much bounce.
Expect to pay more for a good quality latex mattress compared to an equivalent foam or innerspring mattress of comparable quality.
4. Gel Foam Mattress
Gel foam or gel-infused foam is more recent addition to the foam family. In essence, it’s a type of polyfoam that has been enhanced with gel beads.
The addition of the gel in the foam increases the density and can provide a cooling effect. As always, design is very important as the cooling effect of gel can be temporary as the heat is stored in the mattress and is released later in the night back to the sleeper, potentially causing overheating.
Mattress Density vs. Firmness
Many people confuse density and firmness as the same thing when, in fact, they are two different qualities. That said, there can be some similarities between mattresses that are high in density and firmness.
The level of firmness is determined by measuring the indentation load deflection or ILD. The ILD rating refers to the weight of pressure needed to cause an indentation in the foam.
As an example, the 2920 Sleep Mattress uses a very dense foam in its top layer (over 3.5 lb!), but it also has the lowest ILD rating of the 4 layers. The low ILD rating in the top 2” layer can easily be felt as it is very nice and soft when you first lay down on the mattress and provides excellent pressure relief to the hips, shoulders, and other joints. Immediately underneath this soft layer, the next 3 layers of foam become significantly firmer to ramp up the overall support your body needs.
How Does Mattress Foam Density and Firmness Affect Sleep?
Finding the right mattress density will take some research and exploration into your needs and preferences as a sleeper.
By examining factors like your weight, sleeping position, temperature needs, sensitivity to smell, budget, and support needs, you can discover which density is right for you.
Most importantly, when deciding which mattress to purchase the customer service in the store or online should be able to answer your questions as to whether the mattress is a good fit for you based on these factors.
How to Choose Mattress Density and Firmness Based on Your Weight
Firstly, always look for a foam mattress with a foam density of at least 1.7 lb of greater, especially if it has been compressed. Foam mattresses with a 1.5 lb density or less are more likely to breakdown than a mattress with a density of 1.7lb or greater.
Sleepers weighing less than 130 pounds will be comfortable on a softer or lower ILD mattress, and can also look for medium or high density foam mattresses.
Those who are heavier than 300 pounds should opt for mattresses with a high density. The higher density will ensure proper support for the spine and hips. In particular, be open to looking at innerspring options which could be more durable than foam mattresses. Also, be aware that a foam mattress that feels firm to a 150lb sleeper will feel significantly softer for a 300lb+ sleeper so keep in mind whether you prefer a softer or firmer sleeping surface.
Choosing Mattress Density Based on Sleep Position
Sleeping positions can differ from person to person. The sleeping position you prefer to sleep in throughout the night can help you determine which density level will support you best.
Here are the three most common sleeping positions and their ideal mattress densities:
- Back sleepers will often find adequate support at any density level
- Side sleepers have the freedom and flexibility to choose between all density levels, and heavier sleepers should look for slightly firmer options.
- Stomach or front sleepers need a high density, and often firmer, mattress to ensure their spines are properly aligned
The Best Mattress Density for Warm and Cool Sleepers
If you’re the kind of person who releases and generates a large amount of heat while you sleep, choose a mattress with a top layer of foam specifically designed to manage heat. Open cell foams in particular allows for more cool airflow and for the heat released from your body to disperse.
A closed cell foam, especially if it is a high density foam (think memory foam) is more likely to create a more solid barrier to trap your body heat.. ..leading to the dreaded memory foam overheating!
Heavy vs. Light Sleepers
Regardless of whether you are a light or heavy sleeper, foam mattresses are excellent at muffling sound and motion disturbance. This quality makes foam mattresses a good choice for couples and co-sleepers.
While low, medium and high density foams all do a good job of softening disturbances, high density mattresses are slightly more effective in this regard.
Sensitive Noses, Cost, and Durability
In the case of memory foam and gel foam, a higher density is also an indication that additional chemicals and materials have been used in the manufacturing process. These additional materials can be quite odorous and may need to be aired out before use.
Higher density foam mattresses are usually more expensive than low and medium density foam mattresses.
Finally, high density foam also tends to be more durable and long-lasting than lower density foam. The elastic nature of the foam allows it to recover and regain its shape more easily.
Above all, always make sure the mattress uses 100% Certi-PUR US foams. This ensures the foams used meet indoor air quality standards and avoid the use of certain toxic chemicals.
The 2920 Sleep mattress uses 100% Certi-PUR US foams sourced in the USA, and the mattress is made in the USA.
Which Foam Mattress Density Is Right for You?
By understanding mattress foam densities you will be able to make an informed decision when it comes time to purchase a new mattress. Remember, higher doesn’t always mean better.
Consider vital factors like cost, support needs, your sleeping position, your weight, and what you need to stay comfortable throughout the night. Finding the answers to all of these questions will ensure you the perfect mattress that is right for you.
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