Online Tool Store
Nyquist Sampling Calculator
Calculate the minimum sample rate for a signal bandwidth, the resulting Nyquist frequency, and what aliasing does when you fall below it.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Math & Science
Nyquist Sampling Calculator
Frontend preview — no upload or external service.
Result
44.1 kHz sampling gives a 22.05 kHz Nyquist frequency, comfortably above an 18 kHz signal. A 30 kHz component would alias down to 14.1 kHz and be indistinguishable from real content.
How the Nyquist Sampling Calculator works
- Enter the highest frequency you need to capture accurately.
- Check the proposed sample rate gives a Nyquist frequency above it, with margin for the anti-alias filter's transition band.
- Look at where out-of-band content would alias to — that is what an anti-alias filter exists to remove before sampling.
The method
A sampled signal can only represent frequencies below half the sample rate. Anything above that folds back into the audible range as a false lower frequency.
Nyquist frequency = sample rate ÷ 2; alias frequency = |sample rate − input frequency| for the first fold
At 44.1 kHz, a 30 kHz input appears at 14.1 kHz. It is indistinguishable from a real 14.1 kHz signal after sampling, which is why filtering must happen before the converter.
FAQ
Why is CD audio 44.1 kHz rather than 40?
Because human hearing extends to roughly 20 kHz and a filter cannot cut off instantly. The extra 4.1 kHz gives the anti-alias filter a transition band between the highest wanted frequency and the Nyquist limit.
Can aliasing be removed afterwards?
No. Once folded down, an aliased component is mathematically identical to a real signal at that frequency. It must be filtered out before the converter, which is why anti-alias filters are analogue.
Does a higher sample rate always help?
It eases filter design and helps in processing that generates harmonics. For capture alone, once the Nyquist frequency comfortably exceeds the signal bandwidth, more rate mostly means more data.
How we compare
| Feature | Online Tool Store | A graphing calculator | A stats package |
|---|---|---|---|
| Shows alias frequencies | ✓ | ✗ | ✓ |
| Filter transition band noted | ✓ | ✗ | Sometimes |
| No install | ✓ | ✓ | ✗ |
| Works offline once loaded | ✓ | ✓ | ✗ |
Nyquist Sampling Calculator shows where out-of-band content lands, because aliasing is irreversible once the sample has been taken.