Online Tool Store
MIDI Note Number Converter
Convert MIDI note numbers to note names and Hz frequency and back — accepts sharps and flats, uses the standard C4 = 60 convention.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
MIDI Note Number Converter
Convert between MIDI note number, note name, and frequency. Uses the C4 = 60 convention (A4 = note 69 = 440Hz).
How it works
Every MIDI note number maps to exactly one pitch under equal temperament. The note name comes from the number's position within each 12-semitone octave; the frequency comes from how many semitones it sits from concert pitch A4:
note name = NOTE_NAMES[n mod 12] + (floor(n / 12) − 1) frequency = 440 × 2^((n − 69) / 12)
For example, note 60 lands on "C" within its octave and 4 octaves above the reference point, giving C4 at 261.63Hz — a fifth below A4's reference 440Hz.
FAQ
Why does MIDI note 60 mean C4, not C3 or C5?
This is the "C4 = 60" convention (also called scientific pitch notation), used by this calculator and by most DAWs today. A minority of older software instead uses "C3 = 60" — if a number from a different tool looks one octave off, that's the reason.
How is frequency calculated from a MIDI note number?
From the standard equal-tempered tuning formula: frequency = 440 × 2^((note − 69) / 12), where 440Hz is concert pitch A4 (MIDI note 69). Each semitone is exactly the 12th root of 2 apart in frequency.
Can I enter a flat, like Eb, instead of a sharp?
Yes — Eb4, Ab3, Bb2 and so on are accepted and converted to the same pitch as their sharp equivalent (D#4, G#3, A#2).
What is the full valid MIDI note range?
0 to 127 — from C-1 (about 8.18Hz, below human hearing) up to G9 (about 12,543Hz, above the range of virtually every real instrument). A standard 88-key piano covers MIDI notes 21 (A0) to 108 (C8).
How we compare
| Feature | Online Tool Store | Manual octave/semitone math | A DAW's built-in piano roll tooltip |
|---|---|---|---|
| Converts both directions (number ↔ name) | Yes | One direction at a time | Usually number → pitch only |
| Shows exact frequency in Hz | Yes | Manual formula | Sometimes |
| Accepts flats and sharps | Yes | N/A | Usually |
| Free, in the browser, no DAW required | Yes | N/A | Requires the DAW open |
For a quick lookup while scripting MIDI, tuning a synth, or checking a note's frequency, this is faster than opening a DAW just to hover a piano roll.