Note Frequency Chart
Look up the frequency in hertz of every musical note, with MIDI numbers, piano keys, wavelengths and an adjustable A4 tuning reference.
A4 = 440.00 Hz · Middle C (C4) = 261.63 Hz
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| Note | Frequency (Hz) | MIDI | Piano key | Wavelength (cm) | Period (ms) | Play |
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Frequency → nearest note
- Nearest note
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- Exact pitch
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- MIDI number
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- Deviation
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- Verdict
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Your browser has no Web Audio support, so the play buttons are disabled. Every number on this page still works.
Pitches use twelve-tone equal temperament, f = A4 × 2^((m − 69) / 12), with
scientific pitch notation (middle C = C4 = MIDI 60). Wavelengths assume a speed of sound of
343 m/s (dry air, 20 °C).
How it works
Every frequency here comes from one formula. In twelve-tone equal temperament each semitone is
the twelfth root of two apart, so the pitch of MIDI note number m is
f = A4 × 2^((m − 69) / 12). MIDI 69 is A4, the tuning reference, which is why
changing the A4 box from 440 Hz to 432 Hz shifts the whole chart at once. With A4 = 440 Hz the
standard landmarks fall out exactly as printed in reference tables: A0 = 27.50 Hz, C4 (middle
C) = 261.63 Hz, A4 = 440.00 Hz and C8 = 4186.01 Hz.
The other columns are derived from the frequency. The period is 1000 / f
milliseconds — one cycle of the waveform — and the wavelength is 343 / f metres,
shown in centimetres, using the speed of sound in dry air at 20 °C. The piano key number
counts from A0 as key 1 up to C8 as key 88, so it is blank for notes outside a standard
88-key piano. Names are shown as sharps, flats or both; C#4 and Db4 are the same pitch in
equal temperament.
The frequency finder works the other way round: given a frequency it solves
m = 69 + 12 × log₂(f / A4), rounds to the nearest MIDI note and reports the
difference in cents, where cents = 1200 × log₂(f / f_note) and 100 cents is one
semitone. Anything inside ±5 cents is counted as in tune. Everything is computed in your
browser with plain JavaScript and the play buttons use the Web Audio API locally — nothing is
uploaded, there is no sign-up and there are no ads.
Frequently asked questions
What is the frequency of A4 and middle C?
With the standard concert pitch A4 = 440 Hz, middle C (C4, MIDI 60) is 261.63 Hz. The chart derives every pitch from twelve-tone equal temperament using f = A4 × 2^((m − 69) / 12), so A0 comes out at 27.50 Hz, A4 at 440.00 Hz and C8, the top note of a piano, at 4186.01 Hz.
Can I see the chart at 432 Hz or another tuning?
Yes. Type any reference between 300 and 600 Hz into the A4 box and the whole table retunes instantly. At A4 = 432 Hz middle C becomes 256.87 Hz. That covers 432 Hz tuning, baroque A = 415 Hz and orchestral A = 442 or 443 Hz.
How do I find which note a frequency is?
Enter the frequency in the finder and it solves m = 69 + 12 × log₂(f / A4), rounds to the nearest semitone and reports the offset as cents = 1200 × log₂(f / f_note). For example 450 Hz reads as A4, 38.9 cents sharp; anything within ±5 cents counts as in tune.