Free browser tool
Free AVI to MP4 Converter
Convert old AVI files to MP4 in seconds — no upload, no sign-up, no watermark. Shrink large AVI files and make them play on any device. Everything runs privately in your browser.
- No upload
- No sign-up
- No watermark
- Smaller file size
Quality
Copies the video and audio into an MP4 container without re-encoding. Falls back to H.264 only if the source codec can't live in MP4.
Max resolution
Drop a video here or click to browse
MOV, MKV, AVI, WebM → MP4 — converted locally in your browser
Sponsored by the makers
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Screen Charm is a native macOS app.
How to convert AVI to MP4 online
Drop your AVI file
Select or drag in your AVI file. Processing is local — nothing is sent to a server.
Re-encode to H.264
FFmpeg converts the video to H.264 and audio to AAC — the universal standard for MP4 playback. Choose High, Balanced or Small and optionally cap the resolution to control the file size.
Download MP4
Click Download. The MP4 is typically 50–80% smaller than the original AVI and plays on any device.
Why convert AVI to MP4?
Much smaller file size
AVI files can be enormous. Converting to MP4 (H.264) typically cuts file size by 50–80% with no visible quality difference, making files faster to share and store.
Play on any device
AVI is not supported by iPhones, Android phones, or smart TVs without a third-party app. MP4 plays natively on everything.
Upload to any platform
YouTube, Vimeo, social media, and most CMSs require MP4. AVI uploads are frequently rejected or silently converted at lower quality.
Open in modern editors
MP4 is the default format for Premiere Pro, Final Cut, DaVinci Resolve, and iMovie. AVI often causes import errors or requires a codec pack.
Frequently Asked Questions
How do I convert AVI to MP4 online for free?
Drop your AVI file into the converter or click to browse. Conversion runs locally in your browser — no upload, no sign-up, no watermark. Click Download when done.
What is an AVI file?
AVI (Audio Video Interleave) is a legacy Microsoft format from 1992. Still produced by some older cameras and recorders, but not supported by modern phones, smart TVs, or streaming platforms.
Will I lose quality when converting AVI to MP4?
The converter re-encodes to H.264 + AAC, producing an excellent-looking result at a much smaller file size. For most practical uses the output is indistinguishable from the original.
Is my video uploaded to a server?
No. Everything runs locally in your browser using FFmpeg compiled to WebAssembly. Your file never leaves your device.
Why are AVI files so large?
AVI predates modern compression. Many files use old or uncompressed codecs. Converting to MP4 (H.264) typically reduces file size by 50–80% with no visible quality difference.
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Sponsored by the makers
Tired of boring screen recordings?
Try Screen Charm.
Auto-zoom, captions, motion blur, camera overlay and a vertical layout for Shorts. Record once, export a polished video.
Screen Charm is a native macOS app.