Given the growing demand for harvest residues for energy generation from Pinus radiata forest plantations in south-central Chile, models for estimating site-specific forest residue production are needed. In this study, allometric models were fitted to estimate the potential biomass resulting from the harvest of P. radiata plantations located in volcanic sand, recent volcanic ash and sedimentary soils, taking into consideration management gradients and site productivity, in characteristic sites of south-central Chile. The fitted models allowed estimating conversion factors and developing estimation models at individual tree and stand level. Results suggest that conversion factors for changing from stem biomass to potential residue biomass have a negative exponential relationship with tree size. Models fitted for estimating at individual tree level, starting with diameter and height variables, suggest that the models depend on soil origin, while in the case of stand-level estimates the fitted model is independent of soil origin, gradient management and productivity.