The HPLANE program computes the EM profile response of a perfectly conducting half-plane in free-space for various geophysical dipole-dipole measurement systems. The half-plane can be used to model the EM response of a thin, highly conductive target in resistive surroundings. The computational method is based on the analytical solution presented in the classic book of F.S. Grant and G.F West (1967): Interpretation theory in applied geophysics. HPLANE can be used for educational purposes and as an approximate interpretation tool for geophysical EM measurements.