Density
Weight of a cubic foot of foam.

Examples:

1.2lb density = 1.2 pounds per cubic foot

or

2.0 lb density = 2.0 pounds per cubic foot.

Low Denisty = 1.0 - 1.2lbs

Medium Density = 1.5 -1.9lbs

High Density = 2.0 - 2.4lbs

I.L.D
Indentation Load Deflection.

Measures the degree in pounds of softness or firmness of foam. The 25% I.L.D reading is the number of pounds to achieve a 25% compression of a 4" thick piece of foam using a 50" indentor foot.

Examples:

30lb I.L.D = Takes 30 pounds of pressure to indent foam 25%.

Super soft = 9 lb

Soft = 15 to 21 lb

Medium = 27-30 lb

Firm = 32-45 lb

Extra firm = 45-60 lb

Super firm = 80-100 lb