Note Frequency Calculator
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Convert note names (e.g. A4) to Hz, or Hz to the nearest note — A4 = 440 Hz standard tuning.
Note or frequency
Frequency
440 Hz
A4
- Period
- 2.27 ms
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Notes and frequency
Musical pitch corresponds to vibration frequency in hertz (Hz). Equal temperament divides the octave into 12 semitones, each a factor of 2^(1/12) apart. A4 = 440 Hz is the modern concert pitch reference.
Enter a note like C4, F#5, or Bb3 — accidentals use # or b. Enter Hz to find the nearest note name for tuning and synthesis work.
Example: A4 = 440 Hz. One semitone up (A#4) ≈ 466 Hz. C4 (middle C) ≈ 261.6 Hz.
Common questions
Can I change concert A?
This calculator uses A4 = 440 Hz. Historical baroque pitch used A = 415 Hz; some orchestras tune to 442–443 Hz.
What note format works?
Letter + optional # or b + octave number — e.g. G3, F#4, Bb5. No flats spelled as "Db" — use C# instead.