A fast and simple algorithm is presented for calculating the effects of energy loss and scattering on electrons which pass through a converter foil. This algorithm is designed to be integrated into particle‐in‐cell codes for electron‐beam transport. The results of this algorithm for such quantities as energy and number transmission and reflection coefficients compare very favorably with results obtained from a more sophisticated Monte Carlo transport code for pertinent applications. The savings in time is appreciable: this algorithm is approximately 30 times faster than the more sophisticated code.