Two‐component cortical bone and water, and trabecular bone and water models were used to study the beam hardening errors associated with computed tomography (CT) bone densitometry and sizing methods. Specimens used included a femur, humerus, radius, ulna, and vertebral bodies. A second‐order correction algorithm was employed to improve the accuracy of these quantitative CT methods. Physical measurements of the bones were obtained to verify the CT results. Large discrepancies were found between the uncorrected and second‐order corrected CT assessments of cortical bone density, trabecular bone density, water density within the medullary canal, total bone area, medullary canal area, and cortical area. The interosseous lucent streak was also quantitatively studied. Results showed that second‐order correction significantly improved the accuracy of CT bone densitometry and sizing methods.