I.L.D., " Indentation load deflection", is measured by putting a 15"X15"X4" specimen of foam in an indentometer and measuring the weight required to push the foam down to 25%, 65% and back to 25% of its thickness. Therefore, an I.L.D. rating of 10 lbs. at 25% means that it takes 10 lbs. to compress the foam 25%, 65% I.L.D. compresses the foam 65% and will have a higher figure, then it is brought back to 25% and this is generally the right I.L.D. rating. These days I.F.D, "Indentation force deflection", is sometimes used instead of ILD but means the same thing.

DENSITY - Lbs. per cubic foot is simply the DENSITY of the foam and is not related to I.L.D. at all. You can have a high I.L.D. on a low density piece of foam and conversely a low I.L.D. on a high density foam. The higher the density of the foam, the better the quality and durability of the foam. I.L.D. has nothing to do with the quality, it merely indicates the softness or the hardness of a piece of foam.

Our Vital Foam 5lb Memory foam has an I.L.D. Rating of 10 lbs. and our Vital Foam 6lb Memory Foam has an I.L.D. Rating of 15 lbs.