The maximum amplitude of a waveform corresponding to a particular harmonic spectrum depends on the phases of its harmonic components. A waveform with a low peak‐to‐rms ratio is desirable in situations requiring a maximum signal‐to‐noise ratio. This paper introduces a genetic algorithm‐based method for selecting the phases that produces better results than previously described methods. Results for four different amplitude spectra are given. For the case of a flat spectrum with up to 40 harmonics, the genetic algorithm finds peak factors (peak/√2 rms) ranging from 0.98 to 1.24.