Why AVI files cause trouble today
AVI is a video container that dates back to the early 1990s. It can hold many different kinds of video and audio, and older files may use codecs that modern devices no longer include. That is why an AVI sometimes opens on one computer and fails on another, even though both have the same file extension.
MP4 is the container that phones, tablets, browsers, social platforms, and most editors expect. It is not a guarantee of playback either, since the contents still matter, but it is the safest general-purpose choice.
This tool re-encodes an AVI into a file ending in .mp4 using ffmpeg. You do not choose codecs or bitrate. The tool passes your file and the .mp4 output name to ffmpeg and lets it select its usual defaults for that container.
Typical reasons to convert
The most frequent case is old footage: recordings from a camera, a screen capture program, or an archive of family clips saved as AVI years ago. Phones and many platforms either refuse these files or play them without sound or picture.
Another case is sharing. If you want to send a clip by message, upload it to a site, or open it in a modern editor, MP4 avoids most compatibility surprises.
You may also convert to prepare a file for other tools on this site. For instance, after you have an MP4 you can cut it down with Trim Video or reduce its dimensions. Going the other way, MP4 to AVI handles the reverse conversion if some old device demands it.
How to convert AVI to MP4 with this tool
- Drag your AVI file into the drop area, or click to browse for it.
- Confirm that the file name and size shown are correct. There are no further settings for this converter.
- Click Run. On first use the page loads the video engine (roughly 30MB) and shows a progress bar. After that it says "Processing...".
- Preview the finished video in the player that appears.
- Click Download to save it. The name is your original file name plus "-convert" and the .mp4 extension, such as oldclip-convert.mp4.
Use Start over to clear everything and convert something else.
Limits and practical advice
Your file is processed locally in the browser, so it never leaves your device. Because the work is done by your own computer, big files can take a long time, and very large ones may run out of memory. If you see the error message about memory, split or shorten the clip and try again.
The tool re-encodes with default settings, so there is no way to preserve the exact original quality or to choose a smaller file. As with any re-encoding, expect some quality change and keep the original AVI until you have checked the result.
If the converted file plays but looks wrong, the problem may lie with the source file rather than the conversion. Corrupt or unusual AVI files may fail entirely. Also note that only the first video file you drop is used, since the tool handles one file at a time.