ABSTRACT: This paper describes use of BIOPAK to calculate size classes of live fuels for shrubs and herbs. A library of equations to estimate such fuels in the Pacific Northwest and northern Rocky Mountains is presented and used in an example. These methods can be used in other regions if the user first enters fuel size-class equations for a given region into a new library by using the library editor supplied with BIOPAK. Fuel size classes can be estimated in three ways: (1) When appropriate plant measurements are available, fuel classes can be estimated directly for species that have equations in the library or species with similar growth forms. (2) When appropriate plant measurements are not available, fuel classes can be estimated in two steps, first by estimating total aboveground biomass for individual plants and then by estimating biomass in fuel classes from total aboveground biomass. (3) The equations provided can be used to develop new equations that estimate fuels from plot-level estimates of species cover (and possibly other measures).