This document specifies the methods to be used for the determination of quantity of solid and liquid forms of plant biostimulants in packages, containers or in bulk. This document is not applicable to the quantity determination of: soil improvers, growing media, organic and organo-mineral fertilizers and fertilizing product blends whose main constituent is a growing media or soil improver. The method for quantity determination for these products is given in EN 15761, EN 15238 and EN 12580.