A clean sine-wave reference tone at a precise pitch — for tuning an instrument by ear, checking a tuner's accuracy, or exploring alternate tunings like A432.
The Tuning Reference Generator plays a steady reference note for tuning guitars, violins, pianos and voices: any note from C2 to B6 with a selectable A4 reference — 440 Hz standard, 442 Hz for many orchestras, 432 Hz, or 415 Hz for Baroque.
The exact frequency is displayed, a sine, triangle or sawtooth is available (saws are easy to hear over an instrument) and the Loop button keeps the note sounding as long as you need.
Frequency = A4 × 2^((MIDI − 69)/12). With A4 = 440 Hz, E2 is 82.41 Hz and middle C is 261.63 Hz; with A4 = 432 Hz every pitch is 1.818% lower. Tones are generated with a band-limited oscillator and 4 ms fades.
Reference E, A, D, G, B, E.
A = 442 Hz.
Check pitch.
Find the starting note.
| Notes | C2–B6 |
|---|---|
| A4 reference | 415, 430, 432, 440, 442, 444 Hz |
| Duration | 2–120 s |
ISO 16 standardised it in 1955.
It is a different reference; there is no proven acoustic or health advantage.
It's the internationally standardized pitch for the note A above middle C — 440Hz — that most modern instruments are tuned relative to.
A432 tunes the same note to 432Hz instead of 440Hz, shifting everything slightly lower. Some musicians prefer it for subjective/aesthetic reasons, though it isn't the mainstream orchestral standard.
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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