AVI to MP4 Converter
Runs in your browser — your files are never uploaded.
Turn an old .avi file into a modern, universally-playable MP4. AVI typically holds older codecs (like MJPEG or DivX) that MP4 can’t contain directly, so this tool re-encodes to H.264/AAC — using a real copy of ffmpeg compiled to WebAssembly, running entirely on your device.
OptionsResolution: Original
How to convert AVI to MP4
- 1
Drop your AVI file onto the box, or click to choose one.
- 2
OkConverter re-encodes it to H.264 video / AAC audio locally.
- 3
Click “Download” to save the MP4.
Share
Embed this tool on your site
Paste this where you want the tool to appear. It runs entirely in your visitor's browser — no uploads, no account, no tracking.
Please keep the attribution line — it's what keeps these tools free.
Need a different size, a dark theme, or a different tool? Build an embed lets you preview it first.
Frequently asked questions
Will the MP4 be smaller than my AVI?+
Usually, yes. AVI often wraps older, less efficient codecs, while the H.264 video this tool produces compresses far better — so the MP4 is frequently much smaller at similar visual quality.
Does converting reduce the video quality?+
Re-encoding is lossy, so there’s some quality cost in principle, but H.264 at a sensible quality level makes it visually hard to spot. You can’t recover detail the original AVI codec had already discarded.
Why does this always re-encode instead of remuxing?+
AVI almost always holds codecs (MJPEG, DivX, XviD, uncompressed PCM) that an MP4 container can’t hold directly, so a fast remux essentially never applies — a full re-encode is the normal path here.
Is my video uploaded anywhere?+
No. The one-time ~31 MB engine downloads once per session, but the video itself is never uploaded — the re-encode happens entirely inside your browser tab.