Window Function Comparator

Overlay the classic FFT windows and compare lobe width against sidelobe rejection.

main lobe in bins · peak sidelobe in dB · ENBW in bins
top: window shape (time) · bottom: frequency response, dB vs. bins from center

Choosing a window

Every window is a compromise between three numbers: the main-lobe width (how blurred frequencies become), the peak sidelobe level (how much a strong tone leaks over its neighbours), and the ENBW (how much noise each bin collects). The rectangular window has the sharpest lobe but only −13 dB sidelobes; Hann is the all-round default at −31 dB; Blackman buys −58 dB rejection with a 1.7× wider lobe; flat-top is nearly useless for resolving tones but reads peak amplitudes to within 0.01 dB, which is why calibrators love it. Pick the window for the question you're asking — resolution, dynamic range, or amplitude accuracy.

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