This article describes an offline calibration methodology, resorting to a three-axis rate and positioning table, for high-grade inertial measurement units that encompass three sets of triaxial sensors: advanced fiber optic gyroscopes sensitive to the Earth's rotational velocity; low-noise accelerometers; and integrated magnetometers. The calibration routine, which is similar for all sensory devices, yields three constant parameters a correction matrix, a bias vector, and a reference vector related to a known inertial quantity. Experimental results are presented, featuring the calibration of both high-grade rate gyros and accelerometers, that allow verification of the effectiveness of the proposed method.