Data obtained from solid state cultivations are usually expressed with respect to initial dry weight (IDW) of samples. A new, convenient method to achieve this goal, based on measurement of volatile compounds produced during a process, is proposed. Results obtained during cultivations of Aspergillus candidus on buckwheat grains, where carbon dioxide is shown to be the sole vaporizable metabolite synthesized, demonstrates the feasibility of this approach. In experiments in which the DW/IDW ratio decreased from unity to about 0.7, this method gave results that are similar to the more laborious grain counting method.