Objectives of this study were to test existing prediction equations for duff depth reduction, percentage of duff consumed, and mineral soil exposure to determine the limits of their applicability, and to develop if possible broadly based prediction equations for use throughout the U.S. and Canada. Data from 17 separate studies involving almost 450 prescribed fires in the U.S. and Canada were examined. Performance of existing equations was evaluated by comparing predicted and observed consumption. A number of equations predicted consumption with little bias but low precision. Duff consumption decreased with increasing duff moisture content. Duff consumption was proportionally less in deep duff profiles. Consumption of duff derived from long needled species differed from consumption of duff from short needled species. Predictions of percentage of duff consumed, duff depth consumption and mineral soil exposure left much unexplained variation. However, a fairly robust equation was developed for predicting residual duff depth. © by the Society of American Foresters. Abstract reproduced by permission.