Musical Note to Frequency Calculator

Each note has a MIDI number n = 12 x (octave + 1) + semitone. The frequency is f = A4 x 2^((n - 69) / 12), where A4 (MIDI 69) is the tuning reference.

Equal temperament divides the octave into twelve equal steps, so each semitone is the twelfth root of two apart. It lets every key sound consistent on fixed-pitch instruments.

Some players tune to 432 Hz or to historical pitches like 415 Hz for baroque music. Set the A4 reference and every note is recalculated to match.

Cents measure how far a frequency sits from the nearest note. There are 100 cents per semitone, so a reading of +20 cents means the pitch is one fifth of a semitone sharp.

Middle C is C4 in scientific pitch notation, at 261.63 Hz when A4 is 440 Hz. The A directly above it is A4 at 440 Hz.