MP4 to AVI
MP4 is today's universal video format, but some older software, hardware, and Windows-era workflows still demand AVI, Microsoft's classic container. Maybe a legacy editor won't import MP4, an old media player refuses it, or a device on the shop floor only reads AVI. Converting MP4 to AVI re-encodes your modern H.264 video into a format those established tools accept. Because AVI conversions usually target older codecs, expect a larger file, but one that opens where MP4 wouldn't. FluidConvert handles the whole process in your browser, free, with no account, no install, and no watermark, so your MP4 finally works in the older Windows applications and devices that still rely on AVI.
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Accepts: video/mp4, .mp4 · Max 1GB · always free
Your files are encrypted with TLS and automatically deleted after conversion.
Simply upload your .MP4 file and we'll convert it to .AVI format — fast, free, and secure.
Fast & Free
Convert files up to 1GB completely free. No account, no limits.
Secure
Files are encrypted and automatically deleted after conversion.
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Industry-leading conversion with no quality loss.
How to Convert MP4 to AVI
Upload Your File
Click the upload area above or drag and drop your .MP4 file. We support files up to 1GB, completely free.
Choose Output Format
Select .AVI as your target format. Adjust any conversion settings if needed.
Download Your File
Click Convert Now and wait a few seconds. Once complete, download your converted file instantly.
About MP4 to AVI
Last updated: August 2026
What is MP4?
MP4 (MPEG-4 Part 14) is the dominant modern video container, standardized in 2001 and built to hold efficient codecs like H.264 and H.265 alongside AAC audio. It streams well, supports metadata and subtitles, and plays natively on virtually every phone, browser, TV, and app made in the last two decades. Its combination of small file size and broad compatibility made it the default output for cameras, editing software, and streaming platforms alike. When people say a video file just works, they usually mean MP4. That ubiquity is exactly why converting away from it is only needed for older systems.
Why convert to AVI?
You'd convert MP4 to AVI when a specific older or Windows-native program requires it. Some legacy editing suites, industrial and scientific capture tools, digital signage players, and vintage hardware were built before MP4 existed and only ingest AVI. Rather than reject those systems, converting your modern MP4 into AVI lets you keep using established equipment and software. AVI's simple, long-standing structure means it is still recognized by a wide range of older applications that never added MP4 support, making it the compatibility bridge to legacy environments.
What to expect from the conversion
MP4 to AVI is a lossy re-encode. Your H.264 video is decoded and re-compressed into a codec the target AVI-based tool expects, which is usually older and less efficient than H.264. That means the resulting AVI is typically noticeably larger than the source MP4 at similar quality, and a small amount of detail is discarded during re-encoding. Audio is re-encoded too. MP4 features like chapter markers, soft subtitles, and rich metadata don't carry into AVI's simpler container. The core video and audio, and their sync, are preserved for playback in legacy software.
How FluidConvert handles it
Your MP4 is decoded and re-encoded into a compatible AVI on secure servers, tuned to keep quality as high as the target codec permits. Uploads are encrypted in transit and automatically deleted from our servers about an hour after processing. The conversion is free, needs no account, and adds no watermark.
Common reasons to convert MP4 to AVI
- Importing MP4 footage into a legacy Windows video editor that only accepts AVI
- Playing a modern MP4 on old hardware or a media player that reads only AVI
- Preparing video for an industrial, scientific, or signage system built around AVI files
- Supplying AVI to an established archive or workflow that never adopted MP4
- Making a downloaded MP4 usable in vintage software that predates the MP4 standard
Frequently Asked Questions
Why is my AVI file larger than the original MP4?
MP4 uses H.264, a highly efficient codec, while AVI conversions usually target older codecs that need more data for the same picture. Re-encoding the same footage into one of those codecs inflates the file, sometimes several times over. The larger size is the cost of compatibility with legacy software. If your target tool accepts a modern codec inside AVI, the file stays smaller.
Does converting MP4 to AVI lose quality?
Yes, some. The H.264 video in your MP4 is decoded and re-compressed into AVI's expected codec, and that re-encoding discards a bit of detail. At good settings the loss is minor and often not noticeable in normal viewing. Converting won't improve quality, so keep the MP4 as your master and use the AVI only for the older system that requires it.
When do I actually need AVI instead of MP4?
Only when a specific program or device demands it. Legacy Windows editors, some industrial and lab capture systems, older digital signage players, and vintage hardware may reject MP4 and require AVI. For everything modern, phones, browsers, TVs, and current software, MP4 is superior. Convert to AVI when you are working with older technology that never supported MP4.
Will subtitles and chapters from my MP4 be in the AVI?
No. AVI is a simpler container that doesn't handle soft subtitles, chapter markers, or rich metadata the way MP4 does. FluidConvert preserves the main video and audio, but those extras are dropped in the conversion. If you need subtitles in the AVI, they would have to be permanently burned into the picture, which is a separate process.
Can I play the converted AVI on a Windows PC?
Yes. AVI is a native Windows container, and a MP4 to AVI conversion targets a codec that Windows Media Player and similar tools decode. That is the main reason to convert: to run video on older Windows software or hardware that couldn't open the MP4. On modern devices, though, the original MP4 will play better and take less space.