Convert AVI to MP4
Convert AVI to H.264 MP4 in this browser tab. No file upload, no watermarks. Keep the original and check the downloaded result in your target player.
Drop the avi file
Add your AVI video by dragging it in or browsing. It stays on this device.
Confirm MP4
The video is re-encoded as MP4 using an encoder running in this tab.
Download
The MP4 file saves straight back - no upload, no queue, no copy kept.
AVI conversion steps, tested outputs and limitations
Why convert here, not there
No upload, ever
Cloud video tools take your avi onto their disks. This one keeps it in your tab.
Local conversion
No video upload phase. Click Convert to MP4 to start; the browser may need to download the engine first. Time depends on your device and file.
No account, no daily cap
No queue position, no throttling, no watermark burned into the mp4.
The two formats, briefly
| AVI | AVI is a container that can hold different video and audio codecs, including compressed or uncompressed streams. The .avi extension alone does not tell you the quality, file size or whether a player can open it. | |
|---|---|---|
| MP4 | MP4 is a container, and its extension alone does not guarantee playback. This converter writes H.264 video with AAC audio when audio is present. Many modern players support that combination, but codec profile, resolution and device limits still matter. | |
When you need this
- Your AVI will not play on the TV, phone, or console where you need it.
- Preparing video in the MP4 format a colleague or platform expects.
AVI vs MP4: what changes
| AVI | MP4 | |
|---|---|---|
| Kind | Video | Video |
| Compression | Depends on source encoding | Depends on output encoding |
| Typical size | Depends on the file and encoding settings. | Measure the exported file; it may be larger. |
| Opens on | Check the source in your app and browser. | Check the downloaded file in the receiving app. |
| Best for | Keep the original as your source. | MP4 workflows, subject to the limits below. |
Keep the original. Compare the exported file before sharing or replacing it.
Tested on this tool
On 3 November 2026 we ran a synthetic test file through this converter: an 8-second, 640x480 AVI (MPEG-4 video with MP3 audio), 2,472,282 bytes. The output was a 961,992-byte MP4 - H.264 video at the same 640x480 resolution plus a mono AAC audio track at 44.1 kHz, 8.04 seconds - and the downloaded file decoded cleanly when we checked it.
- Both the picture and the sound carried over, re-encoded to H.264 and AAC rather than copied unchanged.
- The output was smaller than the source for this file. That is this particular test clip, not a rule - re-encoding can also make a file larger.
One small synthetic file is not every AVI. DivX or Xvid video, multiple audio tracks and embedded subtitles were not part of this test, and a phone browser can hit memory limits before a desktop does.
Good to know
- Balanced is the default. It keeps the source dimensions but re-encodes video with lossy H.264 compression, so it does not preserve the original quality exactly. Choose High or Max quality for less compression; output can be larger.
- This conversion uses lossy H.264 video and AAC audio - keep the original AVI as your master if the content matters.