MIDI ↔ Frequency Converter

Convert MIDI note numbers to frequency (Hz), or frequency to MIDI, with adjustable A4 tuning. Pitch labels are shown to the nearest eighth-tone (25¢).

A4 Tuning A4 = 440 Hz

Common tunings 415 Hz (Baroque) 432 Hz 435 Hz (diapason normal) 438 Hz 440 Hz (standard) 442 Hz 444 Hz Custom…

Select a preset, or choose Custom to type an A4 value.

Custom A4 (Hz)

Enabled only when “Custom…” is selected.

Reset to 440

MIDI → Frequency

MIDI note number ( ≥ 0 )

Formula: f = A4 × 2^((n − 69)/12)

Convert Copy Result Clear

Enter a MIDI number and click Convert.

Frequency → MIDI

Frequency (Hz) ( ≥ 0 )

Formula: n = 69 + 12 × log2(f/A4)

Convert Copy Result Clear

Enter a frequency and click Convert.

Sum & Difference Tones (two MIDI pitches)

MIDI pitch A ( ≥ 0 )

MIDI pitch B ( ≥ 0 )

Calculate

Copy Result

Clear

Computes combination tones using frequency math: f+ = f1 + f2, f− = |f1 − f2|. (Then converts back to MIDI/pitch label.)

Enter two MIDI pitches and click Calculate.

Harmonic Series (from a MIDI fundamental)

Fundamental MIDI ( ≥ 0 )

Fundamental is converted to Hz using the current A4 tuning.

Partials to display

Capped for safety (max: 256).

Generate

Copy Result

Clear

Displays partial number, ratio, frequency, MIDI (raw), and pitch label (nearest 25¢).

Enter a fundamental and number of partials, then click Generate.