What is a .mid file?
MIDI Sequence · Audio · MIDI Manufacturers Association · 1983
A MIDI file contains no recorded sound. It stores note instructions, which notes play, how hard, on which instrument and when, that a synthesizer or software turns into audio. That makes MIDI files tiny and fully editable.
What is a .mid file used for?
Think of a MIDI file as sheet music for a computer: it lists notes, timing, velocity and instrument choices, but not the actual sound. A synthesizer or soundfont produces the audio at playback time.
Because it stores instructions rather than audio, a MIDI file is minuscule, often a few kilobytes for a whole song, and every note can be edited afterward in a music program.
The catch is that the same MIDI can sound quite different from one device to another, since each uses its own instrument sounds.
MIDI is everywhere in music production, and you still meet it in karaoke files and old game and website music.
What opens a .mid file?
The .mid format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Media Player
- MuseScore
- a DAW
macOS
- GarageBand
- MuseScore
- a DAW
Linux
- TiMidity++
- MuseScore
- a DAW
Web
- Online MIDI players
Open a .mid file step by step
- Confirm the file really is a .mid. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
- On Windows, open it with Media Player or MuseScore.
- On Mac, use GarageBand or MuseScore.
- On Linux, try TiMidity++ or MuseScore.
- Still stuck? Convert the .mid to MP3, which opens more widely.
Why can't I open my .mid file?
Almost always because no installed app understands MIDI. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.
The other possibility is that the file is not really a .mid at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.
How to convert a .mid file
You can convert a .mid file to MP3, WAV (by rendering through a synth) using a conversion tool or the export menu of an app that opens it.
What is the .mid file signature (magic bytes)?
A .mid file starts with the hex bytes 4D 54 68 64, which read as MThd in ASCII. Programs identify MIDI by those bytes, not by the filename, so a renamed file still gives itself away.
These are the documented signatures for MIDI. For a full breakdown, see the MIDI file signature page.
| Hex signature | Offset | ASCII | Note |
|---|---|---|---|
| 4D 54 68 64 | 0 | MThd | 'MThd' header chunk |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .mid file?
A MIDI file contains no recorded sound. It stores note instructions, which notes play, how hard, on which instrument and when, that a synthesizer or software turns into audio. That makes MIDI files tiny and fully editable.
Why does my MIDI sound different on another device?
Because a MIDI file only stores which notes to play, not the sound itself. Each device or program renders those notes with its own instrument set (soundfont), so the same file can sound quite different.
How do I convert a MIDI to MP3?
Load it into a program that renders MIDI through a synthesizer or soundfont, such as MuseScore or a DAW, then export the result to MP3 or WAV. There is no direct copy, because the audio has to be generated first.
Related formats
Sources
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