Frequency Aliasing and Sample Rate Calculator

Method, example, and limits

Formula: Let r = f mod fₛ. The folded alias is min(r, fₛ − r), between 0 and fₛ/2; Nyquist frequency is fₛ/2.

Inputs and units: f is nonnegative signal frequency and fₛ is positive samples per second. Frequency units are hertz.

Worked example: For a 700 Hz tone sampled at 1,000 samples/s, Nyquist is 500 Hz and the folded alias is 300 Hz.

Result meaning: A result above Nyquist folds to the lower baseband frequency; 300 Hz here is indistinguishable from the 700 Hz tone in ideal samples at this rate.

Assumptions: The signal is treated as a single ideal sinusoid under uniform sampling. The Nyquist comparison describes the frequency relation, but does not imply a practical anti-alias filter or adequate measurement.

Limits: Real signals may contain multiple components, noise, jitter, nonuniform sampling, and filter effects. Frequencies above Nyquist cannot generally be uniquely identified from samples without prior constraints.