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.
How to open 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
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.
.mid file signature (magic bytes)
Programs recognise a .mid file by the bytes at the start of the file, not by its name. These are the signatures for MIDI. For a full breakdown, see the MIDI file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 4D 54 68 64 | 0 | '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
Details on this page were checked against authoritative references: