How Is Latex Density Measured?

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Density is an important consideration for latex mattress shoppers. This measurement is calculated by determining the mass of a one-cubic-foot section of the mattress, and expressed in pounds per cubic feet (PCF); the results indicates how firm the mattress will feel. Density is also linked to durability and other key factors. This guide will explain how latex density is categorized, discuss the differences between density and indentation load deflection (ILD), and offer some tips for finding the right latex mattress for you and your sleeping partner.

 

What Is Density?

Density is the mass of an object or substance per unit volume. To calculate density, divide its mass by its total volume. Measurements are expressed as: [unit of weight] per cubic [unit of volume]. In the U.S. mattress industry, density is usually expressed in pounds per cubic foot, or PCF; most mattress manufacturers outside the United States measure mattress density in kilograms per cubic meter.

For example: if a mattress has a density of 4 PCF, this means that a section of the mattress measuring one cubic foot will weigh four pounds. To calculate the entire mass of this mattress, simply multiple the total number of cubic feet by four.

 

How Is Latex Density Categorized?

The density of a latex mattress is directly linked to its firmness level. Most latex mattresses sold today have a density ranging from 3.75 PCF (least firm) to 5.93 PCF (firmest); when converted to kilograms per cubic meter, this roughly translates to densities of 60 KCM to 95 KCM.

Generally speaking, latex density is divided into three categories:

  • Low-density latex feels relatively soft on impact, and the material will immediately react to the sleeper’s body. Low-density latex also has a relatively short lifespan.
  • Medium-density latex, unsurprisingly, falls between low- and high-density latex in terms of firmness, responsiveness, and durability.
  • High-density latex is the firmest option, with a slower reaction time. It is also the most durable; for this reason, it is typically used in the support cores of mattresses, rather than the comfort layers.

Two types of latex are commonly found in mattresses manufactured today: Talalay and Dunlop. Generally speaking, Dunlop latex is denser and heavier than Talalay latex. As a result, Talalay is most commonly used in comfort layers, while Dunlop is used in support cores.

 

Latex Density vs. Foam Density

In addition to latex, density is also used to measure foams used in mattresses. However, density measurement ranges vary by material. The table below features density ranges for latex and the two most common foams found in mattresses, conventional polyfoam and memory foam (also known as viscoelastic polyfoam). This table is especially useful for evaluating mattresses that feature latex and foam components.

MaterialLow-Density RangeMedium-Density RangeHigh-Density Range
LatexLess than 4.3 PCF4.3 to 5.3 PCFMore than 5.3 PCF
Conventional PolyfoamLess than 1.5 PCF1.5 to 1.8 PCFMore than 1.8 PCF
Memory FoamLess than 4 PCF4 to 5 PCFMore than 5 PCF

Another key difference is price-point. For foam-based mattresses, higher densities are usually associated with higher costs. With latex beds, however, density does not affect the price as much as the type of latex used. Talalay latex (which tends to be low-density) is usually more expensive than Dunlop latex. Additionally, mattresses made entirely of natural latex typically cost more than mattresses that feature synthetic latex components.

 

What Is the Difference Between Density and ILD?

In addition to density, a measurement known as indentation load deflection (ILD) is commonly used to indicate the firmness of latex mattresses. ILD is calculated by placing a metal disc measuring 50 square inches on top of a mattress to determine how much pressure is needed to indent the material by 25 percent. ILD is expressed in numerals representing the required weight in pounds. The higher the ILD, the firmer the mattress. The table below lists common ILD ranges for latex mattresses.

FeelILD Range
Very Soft16 pounds or less
Soft19 to 21 pounds
Medium24 to 26 pounds
Medium Firm29 to 31 pounds
Firm34 to 36 pounds
Very Firm39 pounds or higher

Please note: some ILD ratings are not listed in the table above because they fall between the general feeling categories. An ILD rating of 27 or 28, for instance, would fall between ‘Medium’ and ‘Medium Firm’.

In foam-based mattresses, density and ILD are independent measurements; a high-density mattress foam could have a low ILD, and a low-density foam mattress could have a high ILD. In latex mattresses, however, density and ILD are more directly correlated: high-density latex will almost always have a higher ILD rating, and low-density latex will almost always have a lower ILD rating.  

 

Key Factors for Latex Density

When shopping for a latex mattress based on its density and ILD, it’s important to take the following factors into consideration:

  • Budget: Although the density of a latex mattress is not directly tied to price-point, mattresses with lower-density Talalay latex tend to cost more than those made with higher-density Dunlop latex.
  • Weight: Sleepers that weigh more than 200 pounds often prefer mattresses made of higher-density latex; otherwise they may experience uncomfortable feelings of sinking into the sleep surface. On the other hand, sleepers that are 130 pounds or less will not experience as much pain and pressure relief on high-density latex because they don’t weigh enough to properly compress the material.
  • Sleep Position: Back-sleepers require spinal support and alignment; mattresses rated as ‘Medium Firm’ are usually the best option. Those who sleep on their sides need a surface that supports their neck, shoulders, hips, and legs; they tend to feel the most comfortable on mattresses rated ‘Medium Soft’ or lower. Stomach-sleepers usually prefer the feel of a ‘Firm’ mattress — though this position is generally not recommended due to associated nerve and joint issues. For couples that sleep in different positions, a mattress with a dual firmness setting might be the most suitable option.
  • Durability: The average latex mattresses will last eight and a half years, which is longer than other mattress types. Mattresses constructed with high-density latex usually have the longest lifespans.
 

Conclusion

By understanding how density and ILD affect the feel of latex mattresses, you will be able to compare different brands and find a model that best suits your comfort preferences.

Testing out mattresses with different densities and ILD ratings is highly recommended for first-time latex mattress shoppers. Most large-sized mattress stores and showrooms will feature a handful of latex models. When looking for latex mattresses online, be sure to reach out to customer service representatives if density and/or ILD ratings are not listed for a particular model.

To learn more about mattress density, please visit our How Is Foam Density Measured? page.

 
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