A new method to estimate a structure's inertia properties using a prototype load cell designed to measure all loads and moments applied to a structure is presented. This prototype six-axis transducer approach employs 32 piezoelectric sensing elements which are arranged to form the load cell. These redundant measurements are used to determine the principal forces and moments from an overdetermined set of equations. Calibration of this multi-crystal load cell is performed with a fixture that utilizes a calibration mass and quasi-free-free boundary conditions. The resulting calibration matrix is a 6×32 transformation from the coupled measurements to a decoupled set of pseudo measurements consisting of the forces acting on a structure. With this transducer and its calibration matrix, a system's inertia properties can be estimated. A thorough discussion of both the calibration and inertia estimation procedure with a experimental test case is presented.