What Is a MIDI File?

How to open, edit, and convert MIDI files

Screenshot of several MIDI files in Windows 10 that open with Windows Media Player
MIDI Files.

A file with the .MID or .MIDI file extension (pronounced as "mid-ee") is a Musical Instrument Digital Interface file.

Unlike regular audio files like MP3 or WAV files, MIDI files don't contain actual audio data and are therefore much smaller in size. For example, a MID file can explain what notes are played, when they're played, and how long or loud each note should be.

Files in this format are basically instructional files that explain how the sound should be produced once attached to a playback device or loaded into a particular software program that knows how to interpret the data.

This makes MIDI files perfect for sharing musical information between similar applications and for transferring over low-bandwidth internet connections. The small size also allows for storing on small devices like floppy disks, a common practice in early PC games.

You can read more about the MIDI file format at MIDI.org: About MIDI.

A file with the .MID file extension might instead be a MapInfo Data file. You can open one with GDAL or Pitney Bowes' MapInfo.

How to Play MIDI Files

MIDI files can be opened with Windows Media Player, QuickTime, Winamp, VLC, WildMidi, TiMidity++, NoteWorthy Composer, WildMIDI, Synthesia, MuseScore, Amarok, Apple's Logic Pro, and very likely some other popular media player applications as well. You can also play MIDI files online with Online Sequencer.

Some of those programs open MIDI files on Linux, too, notably TiMidity++, WildMIDI, and Amarok.

Midi Sheet Music is a portable program (you don't have to install it) that can play MIDI files, too, and it even shows you the sheet music in real time as the audio plays. It also lets you convert the MIDI file to sheet music that you can print or save to your computer as either a PDF or in multiple PNG image files.

Sweet MIDI Player is a MIDI player for iOS (iPhone and iPad), but it plays only 75 percent of the file; you can pay for full functionality. Android users can open MID files with the Fun Fun MIDI Player or MIDI Voyager Karaoke Player app.

If you find that an application on your PC does try to open the MIDI file but it's the wrong application or if you would rather have another installed program open MIDI files, see ourĀ How to Change the Default Program for a Specific File Extension guide for making that change in Windows.

How to Convert a MIDI File

FileZigZag is a free online file converter that can convert MIDI files to MP3, WAV, AAC, FLAC, OGG, WMA, and several other audio formats. Other tools can be used to convert MIDI files as well, which you can see in this list of Free Audio Converter Software Programs.

SolMiRe MIDI to MP3 Converter is another website that converts MIDI files to MP3, but it offers some additional customizations not available through FileZigZag.

The Midi Sheet Music program from above can be used to convert the MIDI file to sheet music.

Still Can't Open the File?

At this point, if you've tried all of the above and none of the websites or programs will open your file, it's important to know that some files share the same letters in the file extension even if their formats are unrelated.

In other words, your file might look like it's MIDI or MID when really it's something similar like MII. In this circumstance, if you really have a MII file, then you have a Wii Virtual Avatar file.

Another file extension that looks a like like MIDI and MID is MDI, used for Microsoft Document Imaging files. MDI files don't work with the programs linked above but instead require Microsoft Office or the MDI2DOC converter (to convert MDI to DOC).

If you already know how to open Musical Instrument Digital Interface files and are instead looking for ways you can download MIDI files, try Hit Trax.