Note to MIDI Converter
Convert between note names and MIDI numbers in both directions, with the frequency for each. Middle C is C4 (MIDI 60) and A4 is MIDI 69. Runs in your browser.
From the note above
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From the MIDI number above
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Show the math
MIDI numbers count semitones from C-1 (note 0), so A4 lands on 69 and middle C (C4) on 60:
MIDI = (octave + 1) × 12 + note index
The frequency follows from the MIDI number with the equal-temperament formula. The two halves are independent, so you can convert in either direction.
Everything is calculated in your browser.
What this does
A note-to-MIDI converter translates between note names and MIDI numbers in both directions, with the frequency for each. Middle C is C4 (MIDI 60) and A4 is MIDI 69.
How to use it
- Enter a note and octave, or a MIDI number.
- Read the converted value.
- See the frequency at A4 = 440.
- Switch direction as needed.
How it works
MIDI counts semitones up from C-1 (note 0), putting middle C at 60 and A4 at 69. Some software labels middle C as C3, shifting octave numbers by one.
MIDI = (octave + 1) × 12 + note index
Example
A4 is MIDI 69; C4 (middle C) is MIDI 60.
Sources & methodology
Last updated .
Frequently asked questions
How are MIDI numbers assigned?
MIDI counts semitones up from C-1 (note 0), so MIDI = (octave + 1) × 12 + the note’s index. That puts middle C (C4) at 60 and A4 at 69.
Which octave is middle C?
This tool uses the convention where middle C is C4 (MIDI 60). Some software labels it C3 instead, shifting octave numbers by one.
Can I convert in both directions?
Yes, enter a note and octave to get its MIDI number, or a MIDI number to get the note name. Both show the frequency at A4 = 440.
Do you store my input?
No. Everything is calculated locally in your browser.
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