The short answer: this tool converts audio into MIDI. It does not turn a MIDI file into MP3, WAV, or any other audio — there is no synthesizer here, no soundfont, no render-to-audio step. If you already hold the .mid, the step from MIDI to a listenable file is a synthesis job (open it in a DAW or a free player and bounce or export to MP3), not an audio-analysis job. What this tool does give you is the opposite arrow: drop a recording and it returns a MIDI file built to the real spec — format 1, 2 tracks, TPQ 480, up to 6 notes per frame, velocity reaching 127 at −2.22 dBFS, and a CSV you can diff note-by-note. So the honest path from a MIDI file to sound is: MIDI → (your synth or DAW) → MP3. We cover the other direction — audio → (this tool) → MIDI — which is what this site is built for.
1. What this tool actually does
It listens to an audio file — MP3, WAV, FLAC, OGG, M4A, or the audio track pulled out of a video — and returns a MIDI file plus a CSV. The detection runs on the real implementation constants, so the output is predictable, not a black box:
- Readable pitch range: notes from 55 Hz (A1) to 1800 Hz (A6). Anything below or above is outside the window and will not be detected — know that before you blame the converter.
- Polyphony: up to 6 simultaneous notes per frame in polyphonic mode; mono mode follows one pitch at a time.
- Velocity: computed from loudness, reaching 127 at −2.22 dBFS; the CSV carries it to 4-decimal timestamps so you can check every note.
- Output format: a standard format-1 MIDI, 2 tracks, TPQ 480 — openable in any DAW or notation app. That is the file your synth or DAW wants as input.
On 11 known-answer clips it measured 86.7% recall / 91.5% precision. That number is about the audio→MIDI step, which is the half this tool owns.
2. What this tool does NOT do
Stated plainly, because the search term “MIDI to MP3” implies an output this site does not produce:
- No audio rendering. It never plays a MIDI file, never loads a soundfont, never exports MP3 or WAV. A
.midin, a.midout. The only thing it can emit is a MIDI file and a CSV. - No notation rendering either. It does not draw a staff or emit PDF/MusicXML — that is a separate job, covered on the MIDI to sheet music page. Neither output (score or sound) is something this tool makes.
- No guessing at intent. It detects pitches and timing from sound. It cannot choose a guitar vs piano timbre for you — that choice lives in your synth, not here.
This is the boundary, not a limitation we hide: the tool is an audio-to-MIDI converter, and we say so on the page instead of promising an MP3 it will not make.
3. The honest path from a MIDI file to an MP3
If your real goal is “a file I can listen to,” here is the route that actually works. Notice this tool is absent from every step — MIDI-to-audio is a different machine:
| Step | You provide | This tool does | Your synth / DAW does |
|---|---|---|---|
| 1. Have the music | A .mid file | — | — |
| 2. MIDI → sound | The .mid | No — no synthesizer, no soundfont | Yes — plays / renders the notes (any DAW, or a free MIDI player) |
| 3. Sound → MP3 | The rendered audio | No — no audio export | Yes — bounce / export to MP3 |
Step 2 is where a synth or DAW earns its place: it assigns a timbre and turns the note events into samples. Step 3 is where that audio is encoded to MP3. Neither step is something an audio-to-MIDI converter performs, because neither step starts from a recording.
4. When to use this tool vs skip it
| Your situation | Use this tool | Use something else |
|---|---|---|
| You have audio, want MIDI | Yes — that is exactly what it does | — |
You have a .mid, want an MP3 | No — no synthesizer, no audio export | A DAW or free MIDI player (MIDI → bounce → MP3) |
You have a .mid, want a score | No — no notation renderer | A notation app — see MIDI to sheet music |
| You have an MP3, want MIDI | Yes — that is the reverse direction this tool is built for | — |
| You want to verify the notes are right | Yes — the CSV gives 4-decimal timestamps | — |
5. "Convert MIDI to MP3" and "convert mid to MP3": what the two phrasings are really asking
Short answer: both phrasings name the same job, and that job is synthesis, not conversion. A .mid holds note events, not sound. Our own writer proves it: a four-note export is 89 bytes containing 4 note-on / 4 note-off pairs, one tempo event, one 4/4 time-signature event, and an end-of-track event for each of its 2 tracks — all on channel 0. There is no waveform, no sample, and no program-change or pitch-bend event. That is why the timbre has to come from your synth or DAW.
The .mid versus .midi spelling changes the filename only. The writer emits one byte array, and a player reads the MThd header and MTrk chunks inside it. A zero-note export is still a valid 53-byte Standard MIDI File; 1 note is 62 bytes, 4 notes 89 bytes, 10 notes 143 bytes. Not one of those bytes says which instrument should play them.
What a recording does leave in the file is timing. We built the same four-note melody twice — once detected from audio on our 11.610 ms frame grid (256/22050), once drawn by hand on exact beats — and diffed the bytes. They differ at 7 byte offsets only, all inside the note-event region of track 2: the recorded onset lands at tick 479, the drawn one at tick 480, where one tick is 1.0417 ms at 120 BPM. A synth inherits that one-tick deviation; it cannot recover a performance the file never recorded.
So the choice splits three ways:
- Stay here if you have sound and want notes: the analysis runs at 22050 Hz with a 2048-point window and a 256-sample hop, searching 55–1800 Hz. That is the only arrow this tool owns.
- Go to a synth or DAW if you hold a
.midand want an MP3: the file contains 0 program-change events and 0 audio samples, so something outside has to supply the timbre and encode the result. - Open a notation app if what you want is a readable page rather than sound: see MIDI to sheet music, or read how the same file is made three different ways for the byte-level comparison.
Why some MIDI players can export MP3 and this converter cannot
A player that bundles a soundfont renders note events into samples and then encodes them; a browser audio-to-MIDI converter never generates audio in the first place. They sit at opposite ends of the pipeline: one reads a recording, the other writes one. The byte-by-byte anatomy of the exported file shows exactly which events a renderer has to work with.
Questions
Can this tool turn my MIDI file into an MP3?
No. It converts audio into MIDI; it does not synthesize or record sound. Take the .mid and open it in any DAW or a free MIDI player, then bounce or export to MP3 — that is the step that makes the audio.
If I already have an MP3, can this tool help at all?
Yes — that is the reverse direction, and it is exactly what this tool does. Drop the MP3 (or any audio) here and it returns a MIDI file and a CSV. The MP3 to MIDI page explains what the conversion keeps and what it loses.
Why doesn't it just play the MIDI and record it?
Because the job here is reading pitches and timing from a real recording, not generating sound. Synthesizing and capturing audio would need a soundfont and an audio engine we do not ship, and the result would be a generic render rather than the note analysis this tool is built to give you.
What format does the MIDI come out in?
Standard format-1 MIDI, 2 tracks, TPQ 480 — the same file any DAW or synth opens. Polyphonic mode holds up to 6 notes per frame; the readable pitch range is 55–1800 Hz. That is the file your synth wants as input for step 2 above.
Is the MIDI good enough to then render to MP3?
On 11 known-answer clips it measured 86.7% recall / 91.5% precision. The CSV lets you audit every note against your DAW before you bounce, so you catch misses instead of printing them into the audio.
This page states the boundary honestly: this tool converts audio to MIDI and does not render MIDI to MP3. Try the audio→MIDI step on the home page — drop a file, get a MIDI and a CSV, nothing uploaded. Need the other direction handled? Your DAW's bounce does it.
Related guides
- MIDI converterWhat is actually inside a MIDI file
- Clean up a converted MIDIThe 5 passes that turn a raw export into a usable part
- MIDI to sheet musicWhat this tool covers, and where the score comes from
- Sheet music to MIDIWhy this tool listens to audio, not reads scores
- Audio to sheet musicWhere a chord's notes actually land, measured
- MP3 to sheet musicWhether the codec moves anything the page would show
- MIDI to WAVWhy the Play button is a synth but not an export
- MIDI to OGGTwo steps, and only one of them changes the sound