IFD (Indentation Force Deflection), also known as ILD, is the measure of the firmness of a foam. It is used in everything from memory foam to car seats. IFD/ILD measure the deflection of a foam under a load. The specific IFD test gives the foam a numeric IFD value. The higher the number, the firmer the foam. This means, for example, that memory foam will have a much lower number than a base foam for a mattress and a car seat will have a higher number than mattress base foam.
We often get asked about the density of the memory foams we use in our memory foam mattress and memory foam topper pads, and once in awhile about their IFD/ILD rating.
And while we are happy to provide this technical data, I want to be clear that these technical specs alone do not give you a real indication of the comfort of a particular memory foam mattress or topper.
Memory Foam Mattress Glossary
Terms You Should Know Before You Shop for a Memory Foam Mattress
Cover – The cover or ticking is the outside of the mattress. In the case of a memory foam mattress, it is a cover rather than a sewn ticking.