Online Tuning Fork: A440 and Other Pitch References

Play an A in a few seconds

1. Open the Sounds tab and choose the continuous A tuning fork.
2. Set the reference frequency: 440 Hz by default, or a preset such as 442 Hz or 415 Hz.
3. Start the tone, then play your A while listening to the beats: the slower they get, the closer you are.
4. If you prefer a visual indication, switch to the tuner: it uses the same reference.
5. Stop the tone when you are done; the setting is saved on your device.

Reference table

What is concert pitch?

A tuning fork is a metal fork that vibrates at a fixed frequency, and concert pitch is the reference chosen to tune a group of instruments. When people say “A440”, they mean that the A above middle C vibrates 440 times per second.

In scientific pitch notation this note is A4; in French solfège it is called La3. Middle C is C4, at 261.63 Hz. Every other note is derived from the A using equal temperament: each semitone multiplies the frequency by the twelfth root of 2.

So the reference is not a “correct” note in itself: it is a convention. Musicians playing together must share the same one, otherwise the whole group sounds out of tune, even if each player is perfectly tuned on their own.

440, 442, 415, 432: why so many references?

A at 440 Hz has been the international standard since the middle of the 20th century. It is the default for tuners, digital keyboards and most recordings of contemporary music.

Many European symphony orchestras tune slightly higher, at 442 Hz, sometimes 443 or 444 Hz. The gap sounds tiny, but 442 Hz is already about 8 cents above 440 Hz: a pianist or woodwind player who arrives tuned to 440 would be slightly flat.

Early music ensembles often use 415 Hz, roughly a semitone below 440, which lets a score be played on a transposing keyboard. You will also find 392 Hz (about a whole tone lower) for some French Baroque repertoire, 430 Hz for the Classical repertoire, and 466 Hz, a semitone above 440, for some older music.

435 Hz is the “diapason normal” adopted in France in the 19th century. As for 432 Hz, it is offered here like any other reference: it sounds about 32 cents lower than 440, with no special property ever demonstrated. Choose it if your band or your recording uses it.

Setting the reference precisely

By default, the reference can be set from 415 to 466 Hz, with presets for common values. Expert mode extends the range from 392 to 470 Hz, to a tenth of a hertz, for special cases: an old pipe organ, a piano that is not exactly at 440, a recording that is slightly off.

You can also calibrate the reference from a real sound: play the A of a fixed-pitch instrument, and the app measures its frequency and makes it the new A. It is the easiest way to match a piano or accordion that cannot be retuned.

Tuning by ear with the continuous A

When two sounds are almost at the same pitch, you hear a regular pulsing: these are beats. Their speed equals the difference in hertz. An A at 441 Hz played against an A at 440 Hz produces one beat per second, and at this pitch 1 Hz is about 3.9 cents.

To tune, play your note together with the tuning fork and adjust until the pulsing slows down and disappears. If it speeds up, you are going the wrong way. The sine tone is the purest; the organ, reed and cello tones contain harmonics that make the beats easier to hear for some instruments.

• For string instruments, tune the A string first, then the others in fifths or with the tuner.
• For wind instruments, warm up for a few minutes first: a cold instrument plays flat.
• For a group, agree on the reference before you start, then set it on every device.