ESDU AERO 00.03.30 gives a single curve, based on an approximate solution of the oblique shock wave equations, that allows the static pressure difference across the shock to be evaluated knowing only the upstream Mach number, gamma, and flow deflection angle. The equation for the curve is given as well as approximations for small and large values of the flow deflection parameter. A sketch shows boundaries, in terms of the upstream Mach number and the ratio of flow deflection angle to that at detachment, of errors of 1, 2 and 3 per cent incurred using that curve compared with exact solutions. Another graph plots the detachment flow deflection angle against upstream Mach number from 1 to 20 and gamma from 1 (to aid interpolation) to 1.67.