This document specifies methods for the calculation of the dry matter fraction of sludge, sludge products, treated biowaste, soil and waste for which the results of performed analysis are to be calculated to the dry matter basis. Depending on the nature and origin of the sample, the calculation is based on a determination of the dry residue (Method A) or a determination of the water content (Method A & B). It applies to samples containing more than 1 % (mass fraction) of dry residue or more than 1 % (mass fraction) of water. Method A applies to sludge, sludge products, treated biowaste, soil and solid waste. Method B applies to liquid waste and to samples which are suspected or known to contain volatiles except for water.