About this converter

MP3 to MIDI Converter is a free page on this site that turns an audio file into a MIDI file. Give it an MP3, WAV, FLAC, OGG, M4A, or the audio track of a video, and it writes back a standard .mid file you can open in a DAW or notation program.

It runs on your device, not on a server

There is no upload step. Your browser decodes the file locally with the Web Audio API, the pitch analysis happens in your own browser tab, and the MIDI file is assembled in memory on your machine. The file you drop in never travels to this site or anywhere else. Because of that, there is no account to create, no file size cap imposed by a server, and no queue.

What it is good at

• Single-line material: a vocal take, a flute or sax line, a bass line, a guitar riff, a hummed melody.
• Getting a rough MIDI sketch out of a recording so you can edit it rather than enter every note by hand.
• Working as an MP3 to MIDI converter, a WAV to MIDI converter, or a general audio to MIDI converter without switching tools — it is the same engine for every input.

What it is not

• It is not a format swap. Nothing is being unpacked and re-wrapped; the page estimates which notes were played.
• It does not separate a finished mix into stems. A full song with drums, bass and vocals together will come out as whatever is loudest at each moment, usually the bass.
• It does not recover lyrics, dynamics, articulation or the exact timing of a human performance.

How the conversion works

Short frames of audio are analysed for their fundamental frequency using the YIN autocorrelation method. Frames that are not clearly periodic are treated as silence. Consecutive frames that agree on a pitch become one note, and its loudness becomes the MIDI velocity. The result is written as a standard MIDI file (SMF format 1, 480 ticks per quarter note) with the tempo you set inside it.

Keeping it free

The page is offered free and without a watermark or a conversion limit. Running the work on your device instead of on our servers is what makes that practical.

Questions, or something that looks wrong? Write to [email protected].