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Note frequency chart
The frequency of every note from C0 to B8, with A4 = 440 Hz or the reference you choose. Type a frequency to find the nearest note.
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How the frequencies are calculated
In equal temperament the octave is split into 12 equal half steps: each note is the previous one multiplied by the twelfth root of 2 (about 1.05946), and an octave up doubles the frequency. Starting from the reference A4 = 440 Hz:
f = 440 × 2(n − 69) / 12
where n is the MIDI note number (A4 = 69, middle C = 60). So C4 is 261.63 Hz and A5 is 880 Hz.
A different reference pitch
440 Hz for A4 is the standard tuning frequency (ISO 16). If you tune to another reference (for example, A4 = 442 Hz), type it and the whole table changes.
From frequency to note
The nearest note to a frequency is n = 69 + 12 × log₂(f / 440), rounded. The remainder is given in cents: a cent is a hundredth of a half step, so +20 cents means 20% of a half step sharp.
Frequently asked questions
What is the frequency of middle C?
261.63 Hz, with A4 = 440 Hz.
Why is A4 440 Hz?
It's the standard reference pitch for tuning, set in the international standard ISO 16.
What is the frequency of the low E string on a guitar?
The open low E is E2: 82.41 Hz with A4 = 440 Hz.