A440: the 440 Hz tuning note
A440 is the A above middle C, A4, tuned to 440 Hz: the pitch most of the world tunes to, also called concert pitch. Tuners, pianos and music apps work out every other note from it.
Where 440 Hz came from
For centuries there was no standard: an A could be anywhere from about 400 to over 460 Hz, depending on the city and the decade. An international conference in London in 1939 agreed on 440 Hz, and the International Organization for Standardization made it its standard, ISO 16, in 1955 and again in 1975.
Who tunes higher or lower
Many orchestras in Europe tune a little higher, to 442 or 443 Hz, for a brighter sound. Groups playing music from the 1700s on old instruments often tune to 415 Hz, about a semitone lower. Some musicians choose 432 Hz.
How to tune to A440
Set a tuner to 440 Hz, the setting most come with, and tune each note until it reads in tune. To tune by ear, play A440 here and match it.
On a guitar the A on the first string’s fifth fret is A4, 440 Hz, and the open A string is A2, 110 Hz, two octaves lower.
A in every octave
Each A is twice the frequency of the one below it.
| Note | Frequency |
|---|---|
| A0 | 27.5 Hz |
| A1 | 55 Hz |
| A2 | 110 Hz |
| A3 | 220 Hz |
| A4 (A440) | 440 Hz |
| A5 | 880 Hz |
| A6 | 1,760 Hz |
| A7 | 3,520 Hz |
| A8 | 7,040 Hz |
Any note’s frequency
Pick a note and an octave, or type a frequency for its note. Every note is on the note frequency chart.
Equal temperament, the tuning of a piano and of almost all music: each note is the twelfth root of two higher than the one below.
Questions
What is A440?
The A above middle C, A4, tuned to 440 Hz. It is the note orchestras tune to and the one every other note’s frequency is worked out from.
Why is A tuned to 440 Hz?
Instruments and orchestras needed one pitch to play together, and 440 Hz was close to what many already used. There is nothing special about the number itself.
What is concert pitch?
The pitch an orchestra tunes to, A4 at 440 Hz in most of the world. On a concert-pitch instrument such as a piano, a written C sounds as C; on a B♭ trumpet, a written C sounds as B♭.
What note is 440 Hz?
A4, the A above middle C. 880 Hz is A5, an octave higher, and 220 Hz is A3, an octave lower.
Play the notes in a beat
Open the free editor and every note is a key on its piano roll. Drums, bass, chords and a melody, each its own part.
Keep going
More music tools
Piano chords
See how piano chords are built and hear them on a keyboard.
Learn a chordChord finder
Tap piano keys and find the chord those notes make.
Name your chordCamelot wheel
Look up compatible keys for a smoother mix.
Match your keysChord progression generator
Pick a mood and key, hear the chords as a beat, then build on them.
Find your chordsBPM and key finder
Estimate the tempo and musical key of an audio file in your browser.
Check a trackChords, melodies, tempo, keys, names and the editor, all in one place.
All music tools