Indentation Load Deflection (ILD)

Indentation Load Deflection or ILD refers to a measurement of the firmness of a layer of foam. The ILD number represents the amount of force in pounds required to compress the foam by 25%. ILD of 14-22 is generally considered soft; 23-29 medium; 30-37 firm; and 38 and higher extra firm. Also referred to as Indentation Force Deflection (IFD)