Bandwidth from Quality Factor
The quality factor (Q) of a resonant circuit or system describes how sharply it’s tuned around its resonant frequency. Bandwidth relates to Q by BW = f0 / Q, where f0 is the center (resonant) frequency. A higher Q means a narrower bandwidth and a sharper, more selective resonance.
The lower and upper cutoff (half-power) frequencies are found by subtracting and adding half the bandwidth from the center frequency. This relationship is used throughout electronics and acoustics — from tuning radio receivers to designing filters and analyzing mechanical resonators.
Last reviewed August 2026