Music & Acoustics

Intermediate

Equal-Temperament Note Frequency

Frequency of a note n semitones from a reference pitch.

Formula

f_n = f_0 \times 2^{n/12}

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Variables

f_nNote frequency (Hz)

f_0Reference frequency (Hz)

nSemitones from reference

Example

A4=440 Hz, 3 semitones up: f = 440×2^{0.25} ≈ 523.3 Hz (C5)

Did You Know?

Splitting the octave into 12 equal steps was a compromise — it makes every key sound equally (slightly) out of tune.

music frequency pitch note

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