Compress AVI files
The format of camcorder tapes and old archives — modernized. Shrink an AVI on your own device into an MP4 your phone actually plays.
Drop your video here
or
MP4, MOV, WebM, MKV, AVI and more — any size, no upload
🔒 Files never leave your device — everything runs in your browser.
AVI files are time capsules: camcorder transfers, old family archives, downloads from another era of the internet. They are also spectacularly inefficient — the codecs of that period needed several times the bits that modern H.264 uses for the same picture, which is why a standard- definition home video can somehow weigh 2 GB.
That inefficiency is your gain: re-encoding an old AVI with a modern encoder routinely cuts it to a fifth of its size or less at the same visible quality, while converting it into an MP4 that today's phones, TVs, and cloud services all play natively. The whole process runs on your own machine — fitting for files that are often irreplaceable family memories.
How it works
- Drop your file
Any common format, any size. Nothing is uploaded — the tool runs in your browser.
- Pick your target
Use the presets above — this page's defaults are tuned for compress avi — or type any size.
- Download
Your converted file is ready on your device — nothing to wait for, nothing to delete from a server.
Frequently asked questions
Why are my old AVI files so large for such low quality?
They were encoded with 1990s–2000s codecs that needed far more data per frame than modern ones. H.264 achieves the same standard-definition picture in a fraction of the bits, which is why compression gains on AVI files are usually dramatic.
Is this safe for irreplaceable family videos?
Your original file is never modified or uploaded — the tool reads it, builds a new compressed MP4 alongside it, and everything stays on your device. Keep the original as your archive master and share the MP4.
Some very old AVI files fail to open — why?
A few use exotic codecs from defunct capture software that browsers cannot decode. The tool will tell you clearly if a file is unreadable rather than producing a broken output; a desktop player like VLC can usually still open such files for conversion.
Is my file uploaded to a server?
No. ConvertUno runs entirely in your browser on your own device. Your file never leaves your computer or phone — there is no upload at all.
Is it really free, with no watermark?
Yes. Processing happens on your device, so serving you costs us almost nothing — no watermark, no account, no file-size limit, no daily quota.