AbstractMeasurement and analysis experiences have highlighted great difficulties in detecting and measuring interharmonics due to their small amplitudes and their consequent vulnerability to spectral leakage of harmonic tones. A new approach that has a general validity and results fully compatible with the latest IEC standard draft is presented. This approach is based on a self‐tuning technique aimed at performing the spectral analysis on a time window whose width is as near as possible to an integer number of the actual period of the fundamental component, so minimizing the effects of spectral leakage on interharmonic estimation. The approach proposed is successfully applied to both numerical and experimental tests.