Music Frequency Note Calculator
Convert
440 standard; 442–443 many orchestras; 415 baroque
Nearest note
C4
261.63 Hz is in tune with C4 (261.63 Hz).
- MIDI note
- 60
- Period
- 3.822 ms
- Wavelength in air
- 1.311 m
- Octave up / down
- 523.3 / 130.8 Hz
Octave 4 in equal temperament
f = A4 × 2^((n − 69) / 12), where n is the MIDI note number. Each semitone multiplies the frequency by 2^(1/12) ≈ 1.0595.
Convert a frequency in hertz to the nearest musical note and how many cents sharp or flat it is, or a note to its frequency, in equal temperament with any A4 reference (440 Hz, 442 or baroque 415), with the MIDI number, period and wavelength in air.
Formula
Worked Example
Middle C is 9 semitones below A4, so its frequency is 440 × 2^(−9/12) = 261.63 Hz. At a sound speed of 343 m/s, one wavelength is 343 ÷ 261.63 = 1.31 m long.
Frequently Asked Questions
What frequency is middle C?
261.63 Hz with the standard A4 = 440 Hz tuning. It is called C4 in scientific pitch notation and is MIDI note 60.
What is a cent in music?
A hundredth of an equal-tempered semitone; an octave has 1,200 cents. Most listeners notice a difference of about 5–10 cents between two notes played one after the other, and tuners usually call a note in tune within ±5 cents.
Why do orchestras tune to 442 Hz?
A slightly higher A gives a brighter sound, and many European orchestras use 442 or 443 Hz. Baroque ensembles often play at A = 415 Hz, close to a semitone below modern pitch, to match period instruments.