Aliasing Frequency Calculator

About this calculator

The Nyquist-Shannon sampling theorem states that a signal must be sampled at more than twice its highest frequency component (the Nyquist frequency, half the sample rate) to be reconstructed without distortion. When a signal is sampled below that rate, its true frequency gets misrepresented as a lower, “folded” frequency — this is aliasing, calculated by reflecting the signal frequency around multiples of the Nyquist frequency until it lands within the valid range.

Aliasing shows up as jagged edges in undersampled images, the classic “wagon-wheel effect” where spinning wheels appear to rotate backward on video, and false low-frequency tones in poorly filtered audio digitization. Audio engineers, DSP designers, and anyone building an analog-to-digital conversion pipeline use this calculation to choose a sample rate — or design an anti-aliasing filter — that avoids letting high frequencies masquerade as false low ones.