Nyquist Frequency Calculator

The Nyquist frequency is half the sampling rate, that is the sampling rate divided by 2. It is the highest frequency a given sampling rate can represent without aliasing. Sample at 48 kHz and the Nyquist frequency is 24 kHz, so any component above 24 kHz cannot be captured correctly.

The Nyquist frequency is a property of your sampler: it equals half the sampling rate. The Nyquist rate is a property of your signal: it equals twice the highest frequency you want to capture, and it is the minimum sampling rate that avoids aliasing. This calculator reports both so you can compare your chosen sampling rate against what the signal actually needs.

Aliasing happens when a signal contains a frequency above the Nyquist frequency. After sampling, that component folds back and shows up as a lower, false frequency. The calculator flags the risk and reports the apparent frequency using f_apparent = |f minus sampling rate times round(f divided by sampling rate)|, so a 30 kHz tone sampled at 48 kHz appears as 18 kHz.

Keep your highest signal frequency below the Nyquist frequency, which means sampling at more than twice that frequency. In practice you either raise the sampling rate or place an anti-aliasing low-pass filter before the sampler to strip content above the Nyquist frequency. An oversampling ratio above 1 means you have margin to spare.

Human hearing reaches roughly 20 kHz, so the Nyquist rate is about 40 kHz. CD audio uses 44.1 kHz to sit safely above that 40 kHz minimum and leave room for a practical anti-aliasing filter. Enter 44.1 kHz and 20 kHz to see the small headroom this leaves.

No. Every output is a ratio or a doubling of your inputs, so the math is identical whether you work in Hz, kHz, MHz, or GHz. Just keep the sampling rate and the signal frequency in the same unit, and the Nyquist frequency, Nyquist rate, and any alias come back in that same unit.