The mutual radiation resistance between two identical square pistons vibrating in a rigid infinite baffle is numerically determined from the total acoustic power radiated into the farfield. This farfield method is better suited for high-speed numerical computations than the existing nearfield method. Numerical values of the self-radiation resistance for the square piston obtained by this method are in good agreement with those of Burnett and Soroka. Numerical results of the mutual radiation resistance are given for an array of 5×5 identical square pistons vibrating uniformly in a common rigid baffle. The self-radiation resistance and mutual radiation resistance for a more general type of a simple supported square panel having a sine-wave velocity distribution may also be calculated by the same farfield method.