Blog

Questions about beds and mattresses answered & stories told.

In the context of a foam mattress, ILD stands for Indentation Load Deflection. It is a measurement used to assess the firmness or softness of a foam material. ILD is also sometimes referred to as IFD (Indentation Force Deflection).

ILD is determined by measuring the amount of force required to compress a foam material by a certain percentage of its original thickness. This measurement is typically conducted by applying pressure to a circular disc-shaped sample of foam with a specified diameter.

The ILD rating is expressed as a numerical value and is used to classify the foam's firmness. Higher ILD values indicate firmer foam, while lower ILD values indicate softer foam. For example, a foam mattress with an ILD rating of 30 may feel relatively soft, while a mattress with an ILD rating of 50 might be firmer.

It's important to note that ILD is just one factor to consider when evaluating the overall comfort and support of a mattress. Other factors, such as foam density, thickness, and layer composition, also play a role in determining the mattress's feel and performance.