The relative density (or specific gravity) of 1kg of cured silicone is 1.21 (Silastic, Durasil and Smartsil) this yields 50 cubic inches or 819 cubic centimetres (cm). This can be calculated as follows;
100 square inches or 645 square centimetres at 1/2 inch or 12mm thick.
200 square inches or 1290 square centimetres at 1/4 inch or 6mm thick.