Add your files
Drop one AVI or two hundred. Batch conversion is not a paid feature here.
Convert AVI to MP4
Old camcorder footage, a ripped disc or a downloaded file from the 2000s is an AVI, and nothing modern will play it.
Runs on your deviceFreeNo sign-upBatch supported
Where the streams already fit the target container this is a lossless remux, which is close to instant. Otherwise it re-encodes, which in a browser is slow — keep it under a few hundred MB and send long videos to the cloud engine.
Waiting for files/Engine: on-device/Network requests made: 0
What actually changes
AVI and MP4 are not the same picture in two wrappers.
The obsolete codecs inside, usually DivX, Xvid, MPEG-4 Part 2 or uncompressed video, are re-encoded to H.264 and the audio, often MP3 or PCM, is re-encoded to AAC. Files typically shrink dramatically.
Worth knowing first
AVI has no standard way to store variable frame rate or modern timestamps, so video captured from a screen recorder or an old phone can drift out of sync during conversion. If the audio slips progressively rather than by a constant offset, the source frame rate is the cause.
Questions
AVI to MP4, answered
Why is the MP4 so much smaller?
H.264 is fifteen to twenty years newer than the codecs typically found in AVI files, and far more efficient at the same quality.
Will old AVI files look better after converting?
No. The quality ceiling was set when they were made. Converting stops the compatibility problem, not the softness.
How to convert AVI to MP4
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Choose your settings
MPEG-4 Video is lossy, so the quality control decides the trade between size and fidelity.
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Download
Instant, because the file never went anywhere. Nothing expires, since nothing was stored.