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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.
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.
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:
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.
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.
|Material||Low-Density Range||Medium-Density Range||High-Density Range|
|Latex||Less than 4.3 PCF||4.3 to 5.3 PCF||More than 5.3 PCF|
|Conventional Polyfoam||Less than 1.5 PCF||1.5 to 1.8 PCF||More than 1.8 PCF|
|Memory Foam||Less than 4 PCF||4 to 5 PCF||More 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.
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.
|Very Soft||16 pounds or less|
|Soft||19 to 21 pounds|
|Medium||24 to 26 pounds|
|Medium Firm||29 to 31 pounds|
|Firm||34 to 36 pounds|
|Very Firm||39 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.
When shopping for a latex mattress based on its density and ILD, it’s important to take the following factors into consideration:
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.