Convert AVI to MP4
Convert AVI files to MP4 entirely in your browser — no upload, no account, no watermark.
Your file never leaves your device — conversion runs entirely in this browser tab.
To convert AVI to MP4, open the MP4 converter and drop your AVI file in. The conversion runs entirely inside your browser using WebAssembly, so the file is never uploaded. AVI files are usually old, and old codecs compress poorly.
What to expect from this conversion
AVI files are usually old, and old codecs compress poorly. Expect a substantial size reduction — often 60–80% — simply from moving to H.264. AVI also has no native support for modern audio, so the soundtrack is re-encoded to AAC.
A 1992 Microsoft container. Still turns up in archives and old camera output, but lacks modern features and is inefficient by current standards.
Lossy · video
The universal container, normally holding H.264 and AAC. Plays essentially everywhere.
Lossy · video
Both AVI and MP4 discard data to save space, so this conversion compresses something that has already been compressed. Always convert from your original file rather than from an earlier conversion — the losses compound.
How to do it
- Open the MP4 converter
Go to the MP4 converter and drop your AVI file onto it, or click to browse.
- Convert
Press Convert. FFmpeg runs in your browser and shows real progress as it works.
- Download
Download the finished MP4 file. It is created in your browser and never sent anywhere.
Common questions
How do I convert AVI to MP4?
Open the MP4 converter, drop your AVI file onto it and press Convert. Everything runs in your browser — the file is not uploaded. Desktop browsers handle files up to about 200MB; mobile browsers about 40MB.
Does converting AVI to MP4 lose quality?
Yes, some. Both AVI and MP4 are lossy, so this is a second compression pass over data that was already compressed. The loss is usually modest, but always convert from your original rather than from a previous conversion.
Is it free to convert AVI to MP4?
Yes, with no account, no watermark and no daily limit. The processing happens on your device rather than on a server, so there are no per-conversion costs to pass on.
Are my files uploaded when converting AVI to MP4?
No. FFmpeg runs as WebAssembly inside your browser tab. The file is read from your disk, processed in memory and written back out — it never reaches a server.