An extension of the square‐wave excitation method for measuring heat capacity is reported. In particular, attention is focused on the limit where the period of the heat pulse excitation is much smaller than the thermal relaxation time of the calorimeter‐sample system. In this limit, one finds that the thermal ripple induced by the heat pulse is inversely proportional to the heat capacity. This technique allows one to do real‐time heat‐capacity measurements as in the conventional ac technique with the same instrumentation as the square‐wave method. The ripple method is demonstrated with a measurement of the heat capacity of strained Al near its superconducting phase transition.