Look up the exact frequency of any musical note, or find the nearest note to any frequency — a standard A440 reference chart with a reverse lookup.
The Note Frequency Finder converts between musical notes and frequencies. Find the Hz of any note (A4 = 440, middle C = 261.63) or type a frequency and see the nearest note and how many cents sharp or flat it is — with a configurable A4 reference for 432, 442 or Baroque pitch.
It also gives the MIDI number, the period in milliseconds and the wavelength in air.
In equal temperament each semitone is a ratio of 2^(1/12). With MIDI note n (A4 = 69): f = A4 × 2^((n−69)/12). Cents = 1200 × log₂(f ÷ f_note). Wavelength = speed of sound ÷ f, using 343 m/s (air at 20 °C).
Know the target Hz for a string.
Set oscillator pitches.
Wavelengths for room modes.
Identify pitches.
| Tuning | 12-tone equal temperament |
|---|---|
| Reference | A4 400–480 Hz |
| Speed of sound | 343 m/s |
261.63 Hz (A4 = 440).
1/100 of a semitone.
A440 — the modern concert-pitch standard where A4 equals exactly 440Hz.
It means the frequency you entered is 15 cents (15/100ths of a semitone) sharp of that note — useful for checking how far out of tune something is.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
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