AVI to MP4 converter
Convert AVI to MP4 in your browser. The video is genuinely re-encoded to H.264, which is what makes an old AVI play on modern devices.
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Accepts .avi · Up to 20 files at a time · up to 667 MB each "Upload" and "download" here mean your browser reading a file from this device and writing one back to it. Nothing is sent to a server — open your browser's network panel and watch: no request carries your file.
FAQ
Why does this take so much longer than MOV to MP4?
Because it is a real conversion, not a repack. MOV and MP4 hold the same codecs, so the streams are copied. AVI holds codecs MP4 does not accept, so every frame has to be decoded and compressed again — the slow part of any video work.
Will the video lose quality?
A little. Re-encoding compressed video always costs something. At the default quality the loss is not visible on ordinary footage. Raising the quality preset reduces it further at the cost of a larger file.
Why will nothing play my AVI?
The container is not really the problem — the codec inside is. DivX and Xvid predate hardware decoders, so phones and TVs have no silicon for them and increasingly no software either. Converting to H.264 gives the file a codec every device already has.
Is there a file size limit?
About 667 MB. Video conversions are capped by how much has to be held while working — the incoming frames, the outgoing file and the encoder's buffers all share the same memory.
Does the audio get converted too?
Yes. AVI often carries MP3 or AC-3 audio, which MP4 does not accept in the same form, so the audio is re-encoded to AAC alongside the video.
Can I convert several AVIs at once?
Yes, up to twenty. They run one after another rather than together, because each conversion needs its own working memory and running them in parallel would exhaust it.
Is it really free?
Yes — every conversion on this site, with no account, no watermark and no daily cap. The work happens on your own device, so there is no server bill for us to pass on to you.
Do I need to install anything?
No. It runs in any modern browser, on Windows, macOS, Linux, Android and iOS. There is nothing to download and nothing to sign up for, and once the page has loaded it keeps working with the network switched off.
Related converters
- MP4toAVIRe-encodes every frame for the new container
- AVItoMP3Drops the video, re-encodes the audio to MP3
- MOVtoMP4Repackages the same streams — lossless and near-instant
- MKVtoMP4Repackages the same streams — lossless and near-instant
- WebMtoMP4Re-encodes every frame for the new container
- WMVtoMP4Re-encodes every frame for the new container
- FLVtoMP4Re-encodes every frame for the new container
- M4VtoMP4Repackages the same streams — lossless and near-instant