Convert AVI to MP4
Convert AVI to MP4 online free: old camera and DivX videos are re-encoded to H.264 MP4 that plays on every phone and TV. Many at once, no upload. No sign-up.
AVI
AVI is Microsoft’s format from the 1990s. Old digital cameras saved Motion JPEG in it, and DivX and Xvid films were shared as AVI for years.
Those codecs don’t play on phones, smart TVs or in browsers, so an AVI is almost always re-encoded to H.264.
AVI to MP4: remux or re-encode
A AVI with H.264 inside is remuxed in seconds, but most AVI files hold older codecs and are re-encoded to H.264 and AAC, through FFmpeg in WebAssembly.
AVI files are often large for what they show; at the Balanced preset a 1080p minute comes out around 30 MB. Files up to 3 GB are converted, and the FFmpeg path keeps the result in memory, so very long videos need a desktop browser.
How it works
- Drop one or more AVI files: MP4 is already selected. Quality, maximum resolution and sound can be changed before you start.
- Streams that fit MP4 are copied; anything else is re-encoded with WebCodecs, or FFmpeg compiled to WebAssembly when the browser can’t.
- Download each file, or all of them as one ZIP.
Questions
Are my videos uploaded?
No. Reading, remuxing and encoding all run in this browser tab. Open DevTools and watch the Network tab while a file converts: no request carries it.
Why is one file done in seconds and another takes minutes?
A remux only copies the streams, so it runs at disk speed. A re-encode decodes and encodes every frame; FFmpeg in WebAssembly, used when the browser can’t, is slower still.
How large can a video be?
Up to 3 GB per file for free, and as many files as you like. Remuxes and WebCodecs re-encodes stream from the disk; the FFmpeg path holds the result in memory.