Convert AVI to MP4
Modernize legacy AVI videos into MP4 files that play on today's phones, TVs, and browsers. The conversion is done locally - your files are never uploaded.
100% local - your file is never uploaded
Drop your AVI file here, or click to select
Supports video/*,.avi
How to convert AVI to MP4
- 1
Drop your AVI file into the box above, or click it to browse
- 2
Click "Convert AVI to MP4" - processing runs locally in your browser
- 3
Watch the progress bar - nothing is uploaded, so there is no waiting on a network
- 4
Download your MP4 file when the conversion finishes
Why convert AVI to MP4?
AVI dates back to 1992 and typically carries older codecs like DivX, Xvid, or MJPEG that modern devices and browsers no longer bundle decoders for. Converting to MP4 re-encodes the video into H.264, shrinking most old files noticeably while making them playable on anything - and streamable, which AVI was never designed for.
AVI
AVI (Audio Video Interleave) is Microsoft's 1992-era container, common for DivX/Xvid movies, old digital camera clips, and Windows screen recorders of the 2000s. It lacks modern features like streaming support and efficient codecs.
MP4
MP4 with H.264 video is the modern replacement: better compression, universal playback, proper seeking and streaming, and support in every editor and platform.
Frequently asked questions
Why is my converted MP4 smaller than the AVI?
Old AVI files usually use inefficient codecs. H.264 compresses the same visual quality into significantly fewer bytes, so a size drop of 30-70% is common without a visible quality difference.
Can very old or unusual AVI files fail to convert?
Rarely, an AVI with an exotic codec may not decode. The tool uses a full FFmpeg build compiled to WebAssembly, which handles the overwhelming majority of DivX, Xvid, MJPEG, and MPEG-4 variants.
Do I need to install anything?
No. Everything runs in the browser - no codec packs, no desktop converter, no account. It even works offline after the page has loaded once.
Need more options like other formats or quality settings? Use the full Video Converter tool.