About MID Files
MIDI Audio
MIDI stores musical performance data (notes, tempo) rather than audio waveforms.
Family
Audio Files
Extension
.mid
MIME Type
audio/midi
Can Use As
HOW MID
CAME TO BE.
MIDI — Musical Instrument Digital Interface — was drafted in 1981 by Dave Smith and Ikutaro Kakehashi and ratified by the MIDI Manufacturers Association in 1983. The protocol lets electronic musical instruments communicate note, velocity, pitch-bend, and controller data; the .mid (or .midi) file format stores a sequence of those messages with timing information. Crucially, a MIDI file does not contain audio — it contains instructions for how to play something on a synthesizer. What you hear depends on the soundbank your player uses.
For two decades MIDI was everywhere. Early web pages auto-played MIDI background music. Early video games (Doom, Final Fantasy VII, The Secret of Monkey Island) shipped soundtracks as MIDI because a 500 KB .mid could play 90 minutes of music. Sony’s PS1 and Nintendo’s N64 used MIDI-like sequence formats internally. Today MIDI remains the interchange format of professional music production (every DAW speaks MIDI) but is rare as a delivery format to consumers.
CURIOSITIES &
TRIVIA.
A MIDI file stores instructions, not audio — what you hear depends entirely on the synthesizer or soundfont used to play it back.
Dave Smith (creator of MIDI) received a Grammy Technical Award in 2013 for his 1981 proposal that standardized electronic music communication.
The Doom (1993), Duke Nukem 3D (1996), and Final Fantasy VII (1997) soundtracks are all MIDI — billions of virtual orchestras played via synthesizer chips.
MIDI can store 127 different notes and 127 different velocities per channel — ±1 bit more and the spec would have been mainframe-era legacy.
A 90-minute symphony can fit in a 200 KB MIDI file because every note is 4 bytes of data, not audio samples.
STRENGTHS &
LIMITATIONS.
Strengths
- Extremely compact — kilobytes for hours of music.
- Editable in every DAW (Logic, Cubase, Ableton, FL Studio, Reaper).
- Universal hardware interface for electronic instruments.
- 40+ years of stability — MIDI 1.0 files from 1983 still play.
- MIDI 2.0 (2020) extends to 32-bit velocity and polyphonic expression.
Limitations
- Not audio — playback quality varies wildly by synthesizer.
- Cannot represent vocals, samples, or non-synthesizable sounds.
- Web browsers stopped auto-playing MIDI around 2005.
- Consumer listeners almost never encounter .mid as a delivery format.
Typical Sizes & Weights
Pop song (3 min)
10-50 KB
Full game soundtrack (Doom-era)
100-800 KB
Orchestral performance (90 min)
200 KB - 1 MB
Technical Specifications
- MIME type
- audio/midi
- Extensions
- .mid, .midi, .rmi (Microsoft variant)
- Standard
- MIDI 1.0 (1983), Standard MIDI File (SMF) 1.0
- Successor
- MIDI 2.0 (2020)
- Protocol
- Serial MIDI 31.25 kbit/s (legacy hardware)
CONVERT FROM
MID
Common Use Cases
Music composition, sequencing
Related Formats
Popular comparisons
MID vs MP3
Differences, file size, and when to choose each format.
MID vs WAV
Differences, file size, and when to choose each format.
MID vs FLAC
Differences, file size, and when to choose each format.
MID vs AAC
Differences, file size, and when to choose each format.
MID vs M4A
Differences, file size, and when to choose each format.
MID vs OGG
Differences, file size, and when to choose each format.
Popular MID conversions
The most-requested destinations when starting from MID.
Frequently Asked Questions about MID
Frequently Asked Questions
MID (MIDI Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
VLC, foobar2000, and the default media players on Windows and macOS handle MID natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
Upload the MID to KaijuConverter and pick MP3, WAV, FLAC, AAC, OGG, or any other target. Our FFmpeg pipeline decodes the audio and re-encodes to the target format at sensible default bitrates (VBR ~190 kbps for music, 96 kbps for speech). Metadata and cover art travel with the audio where both formats support them.
MID can be lossy or lossless depending on the specific variant. Lossy variants (smaller files) discard some audio detail during compression in ways tuned to be inaudible; lossless variants preserve every sample exactly but produce larger files. For distribution, lossy at high bitrate is standard; for archival, lossless wins.