AVI to MP4 Converter
Convert AVI files to MP4. Processed inside your browser — files never leave your device.
Drop your AVI file here
or click to choose
Choose fileHow to use
- Drop or choose the AVI file to convert.
- The output format is preset to MP4.
- Hit 'Convert to MP4' — it converts inside your browser and downloads right away.
Frequently asked questions
Are my files uploaded to a server?+
No. Conversion happens entirely inside your browser and your file is never sent anywhere — personal videos stay private.
It finished in seconds — did it actually work?+
Yes, that's expected. AVI and MP4 mostly carry the same video data inside, so conversion is often just repackaging. Quality stays identical.
Are subtitles and extra audio tracks kept?+
Tracks the MP4 spec supports are kept; exotic subtitle formats inside AVI may be dropped.
My old AVI looks stretched after converting. What happened?+
Some old AVI files omit aspect-ratio information. The converter keeps the original resolution untouched, so check your player's aspect setting — you may be watching 4:3 source stretched to fill a 16:9 screen.
Is there a file size limit?+
No server limits, but processing uses browser memory, so it's optimized for short clips (tens to a few hundred MB). Files over 300MB show a warning.
Is it really free?+
Yes. No sign-up, no payment, no conversion limits and no watermark.
Can I pick a different output format?+
Yes — on the converter you can switch the output between MP4, WebM, MOV, MKV, AVI and GIF.
Guide
Why convert AVI to MP4?
MP4 is the de-facto standard — it plays on Windows, Mac, iPhone, Android, TVs and in every messenger and website. When a AVI file won't open, won't upload, or your editor can't read it, converting to MP4 fixes it in most cases.
It's the classic "plays for me, not for them" fix — the conversion you need most when sharing AVI files across different devices.
Where do AVI files come from?
Microsoft introduced AVI in 1992, so almost every AVI still around is an old file: camcorder and digital-camera footage from the 2000s, video compressed with DivX or XviD, backups from older CCTV and dashcam units.
The format is too old to carry modern codecs properly and spends far more space on the same picture quality. It was never designed for streaming either, so most web uploads reject it. Converting to MP4 is effectively required to watch old family video or archive footage on current devices.
What happens to quality and size?
When the video data inside your AVI is compatible with MP4 (most cases), the tool just moves it into the new container without re-encoding — zero quality loss, near-identical size, seconds of work.
Only incompatible files fall back to a high-quality H.264 re-encode, and even then the difference is hard to spot in normal viewing.