Note Frequency Calculator
Enter a note name and octave (scientific pitch notation, where middle C is C4) to get its exact frequency in hertz, or switch to the reverse mode to type a frequency and see the nearest musical note, how many cents sharp or flat it is, and its MIDI note number. The A4 reference defaults to the standard 440 Hz but you can change it for alternate tunings such as 432 Hz or 442 Hz used by some orchestras. Frequencies follow equal temperament: f = A4 × 2^((n − 69) / 12). Everything is computed locally in your browser.
How to use
- Pick a mode: note to frequency, or frequency to note.
- Set the A4 reference (default 440 Hz).
- For note to frequency, choose the note and octave; for frequency to note, type a frequency in hertz.
- Read the frequency, nearest note, cents deviation and MIDI number, and copy the result.
Frequently asked questions
- What octave numbering is used?
- Scientific pitch notation: middle C is C4 and A4 is 440 Hz by default. C0 is about 16.35 Hz and C8 is about 4186 Hz.
- What are cents?
- A cent is one hundredth of a semitone. A reading of +20 cents means the frequency is 20 cents sharp of the nearest note; ±50 cents is the half-way point to the neighboring note.
- Can I use a different tuning like 432 Hz?
- Yes. Change the A4 reference and every note is recalculated against it using equal temperament.
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