How to use the AVI to MP4 tool
- Choose the video you want to convert.
- Leave "Fast mode" on when it appears: it changes the container without re-encoding, so it is instant and lossless. Otherwise pick a quality.
- Press Convert.
- Preview the result and download it.
About this tool
AVI (Audio Video Interleave (Microsoft, 1992)) usually holds DivX, Xvid, MJPEG, sometimes H.264 video with MP3, AC-3, PCM audio and is best known for legacy videos and old camcorders. Browser limitation: Chrome, Edge and Firefox cannot open .avi files at all, and most AVI files use DivX, Xvid or MJPEG video that browsers cannot decode. If your AVI cannot be read you will get a clear message instead of a broken file. Safari opens some AVI files. For the rest, use desktop software like VLC or HandBrake.
MP4 with H.264 video and AAC audio is the closest thing to a universal video format. It plays on iPhones, Android phones, Windows, macOS, smart TVs and game consoles, uploads to every social platform, and previews inline in email and chat apps.
Going from AVI to MP4 needs the video to be decoded and re-encoded (to H.264, with AAC audio where your browser can encode it). Your browser's hardware encoder does the work, and the bitrate is capped so the new file is not larger than it needs to be.
Common reasons to convert AVI to MP4
- Rescuing old camcorder and digital-camera clips from the early 2000s.
- Making legacy home video shareable on modern phones and platforms.
- If your browser cannot open the AVI, try Safari or convert it once with VLC or HandBrake; MP4 then plays everywhere.
AVI vs MP4 at a glance
| AVI | MP4 | |
|---|---|---|
| What it is | Audio Video Interleave (Microsoft, 1992) | MPEG-4 Part 14 |
| Typical video codecs | DivX, Xvid, MJPEG, sometimes H.264 | H.264, HEVC, AV1 |
| Typical audio codecs | MP3, AC-3, PCM | AAC, MP3 |
| Best for | Legacy videos and old camcorders | Sharing, social platforms, phones, TVs and email |
| Plays on | Windows players and VLC; limited in browsers | Practically everywhere |
Why use ToolsCrow for this
- Hardware-accelerated. Uses your device's video encoder.
- Private. Files never leave your device.
- No watermark. Free, no account.
- Honest errors. Unsupported codecs are explained, not hidden.
Good to know
- Browser limitation: Chrome, Edge and Firefox cannot open .avi files at all, and most AVI files use DivX, Xvid or MJPEG video that browsers cannot decode. If your AVI cannot be read you will get a clear message instead of a broken file. Safari opens some AVI files. For the rest, use desktop software like VLC or HandBrake.
- Output is H.264 video with AAC audio (or Opus if your browser cannot encode AAC).
Frequently asked questions
Is my video uploaded to a server?
No. Everything runs inside your browser tab using your own device's video hardware. Your file is never sent to ToolsCrow or anyone else, which also means there is no waiting for an upload and it keeps working if your connection drops after the page has loaded.
Is it really free? Is there a watermark?
It is free with no sign-up, no watermark and no daily limits. The only limits are the ones your device sets: memory and processing power.
How large a video can I use?
Because the video is processed on your device, the limit is your device's memory rather than a server quota. Phone clips of several hundred MB are fine on most devices, and desktop computers usually handle 1 to 2 GB. Files over about 4 GB are not supported.
Which browsers work best?
Current Chrome, Edge and Safari (16.4 or newer, including iPhone and iPad) work best because they include the WebCodecs video engine. Recent Firefox versions work for many files. Older browsers fall back to a much slower real-time mode or may not work at all.
Will converting AVI to MP4 reduce quality?
Any re-encode costs a little quality in theory. The High preset is tuned to be visually indistinguishable, and the bitrate is capped to the original so the file does not grow pointlessly.
Why does my AVI file not open?
AVI files usually contain codecs (DivX, Xvid, MJPEG, sometimes H.264) that web browsers were never built to decode. Chrome, Edge and Firefox also cannot open the AVI container. Use VLC or HandBrake to convert it, or try Safari, which opens some.
Why does my result have Opus audio instead of AAC?
Some browsers (for example Chrome on Linux) cannot encode AAC audio. When that happens the tool saves Opus audio instead and tells you. Opus plays in Chrome, Firefox, Edge, VLC and recent Safari; if you need AAC everywhere, run the tool in Chrome or Edge on Windows or macOS, or in Safari.
Related video tools
- Video ConverterConvert a video to MP4, WebM or MOV without uploading it anywhere.
- MP4 to WebMConvert MP4 files to WebM in your browser.
- WebM to MP4Convert WebM files to MP4 in your browser.
- MP4 to MOVConvert MP4 files to MOV in your browser.
- MOV to MP4Convert MOV files to MP4 in your browser.
- Video CompressorShrink any video to a fraction of its size while keeping it sharp, or type the exact size you need in MB.
More in convert video (19 tools), or browse all video tools..