Rubber powders (or granulates) from ground rubber scrap materials are used in many applications in different fields. These applications ask for different properties of the rubber powders, In this paper a number of suggestions to classify powders are given. A reference is being made toward ASTM D5603, that classifies powders with respect to feed stock and sieve analysis. It will be shown that the American situation does not comply as such to the European situation, due to different materials being used on both continents.