Note Frequency Calculator (Pitch to Hz)
Choose a note and octave.
Your numbers
Your results
Frequency (Hz)
Frequency (Hz)
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MIDI note number
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Wavelength in air at 20 °C (m)
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One semitone higher (Hz)
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Period (ms)
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Note Frequency Calculator (Pitch to Hz) by TheCalcTools
How the Note Frequency Calculator (Pitch to Hz) works
In twelve-tone equal temperament each semitone multiplies the frequency by the twelfth root of 2 (about 1.0595), so an octave doubles it. With A4 = 440 Hz, f = 440 × 2^((n − 69) ÷ 12), where n is the MIDI note number.
Some orchestras tune A4 to 442 or 443 Hz, and baroque ensembles often to 415 Hz.
The formula
f = A4 × 2^((n − 69) ÷ 12)
Worked example
Using the default values shown in the calculator:
| Note | A |
|---|---|
| Octave (A4 is concert A) | 4 |
| Tuning reference A4 (Hz) | 440 |
- A4 is 440.000 Hz (MIDI 69), a wavelength of 0.780 m.
Result:
| Frequency (Hz) | 440.000 |
|---|---|
| MIDI note number | 69 |
| Wavelength in air at 20 °C (m) | 0.780 |
| One semitone higher (Hz) | 466.164 |
| Period (ms) | 2.273 |
Frequently asked questions
What frequency is middle C?
C4 is 261.626 Hz with A4 = 440 Hz.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.