This app is designed for the calculation of Z-scores and percentiles for bone mineral content (BMC) and areal bone mineral density (aBMD) for children ages 5–20 years, as measured by dual-energy X-ray absorptiometry (DXA), for the following sites: total body, total-body-less-head, lumbar spine, total hip, femoral neck, and distal ⅓ radius. Separate calculations are available by age, by sex, and by race (Black and non-Black). Height-Z–adjusted Z-scores for these measures are also calculated. The BMC and aBMD data are derived from the Bone Mineral Density in Childhood Study [Zemel B et al., J Clin Endocrinol Metab 2011;96(10):3160–3169]. Calculations are also available for lumbar-spine bone mineral apparent density (BMAD) [Kindler JM et al. J Clin Endocrinol Metab 2019;104(4):1283–1292].