MIDI ↔ Frequency Converter
Convert MIDI note numbers to frequency (Hz), or frequency to MIDI, with adjustable A4 tuning. Pitch labels shown to the nearest eighth-tone (25¢).
A4 Tuning A4 = 440 Hz
Common tunings
Select a preset or choose Custom.
Custom A4 (Hz)
Enabled when "Custom…" is selected.
MIDI → Frequency
MIDI note number (≥ 0)f = A4 × 2^((n − 69)/12)
Enter a MIDI number and click Convert.
Frequency → MIDI
Frequency in Hz (≥ 0)n = 69 + 12 × log₂(f/A4)
Enter a frequency and click Convert.
Sum & Difference Tones
MIDI pitch A (≥ 0)
MIDI pitch B (≥ 0)
f+ = f1 + f2 | f− = |f1 − f2| — then converted back to MIDI/pitch.
Enter two MIDI pitches and click Calculate.
Harmonic Series
Fundamental MIDI (≥ 0)
Converted to Hz using current A4 tuning.
Partials to display
Max: 256
Shows partial number, ratio, frequency, MIDI (raw), and pitch label (nearest 25¢).
Enter a fundamental and number of partials, then click Generate.
MIDI ↔ Frequency Converter · A4 tuning adjustable · Pitch labels to nearest 25¢