Many recent studies have used long bone cross-sectional geometric properties in various comparative analyses. Methods have been described for reconstructing diaphyseal cross sections from external molds and biplanar radiographs that produce accurate results (within 5% of true values on average). The manual image processing required, however, is both time and labor intensive. A new freely available program developed here for the computational freeware, R, automates much of the process. This study compares cross-sectional properties calculated using the new R program to those from peripheral quantitative CT (pQCT) and the original manual method. We find that the R program works aswell as the original manual image processing for most cross sections eliminates the chance for entry errors at several steps and greatly speeds up data collection. Am J Phys Anthropol 142:665–669, 2010. © 2010 Wiley-Liss, Inc.