This tool provides guidance and a stepwise procedure/method to calculate values of fraction of non-renewable biomass (fNRB), which measures the relative amount of wood that is harvested beyond the landscape’s natural rate of regeneration. It may be applied when calculating baseline emissions in applicable methodologies for a project activity or a programme of activities (such as those relevant to clean cooking) that displaces the use of non-renewable biomass under the Clean Development Mechanism (CDM).