Convert AVI to MP4
Convert an older AVI video to a modern MP4 in your browser using the local FFmpeg engine. The first use downloads the converter once, then your AVI is decoded and saved as H.264 video with AAC audio without being uploaded.
Files are converted on your device and never uploaded.
- Price
- Free
- Uploads
- None, it runs on your device
- Sign-up
- Not needed
- Batch
- Unlimited files
- Output
- MP4 (H.264 + AAC)
- First use
- 10 MB download, once
How it works
How to convert AVI to MP4
Add your AVI files
Drop AVI files onto the converter, click to choose them, or paste from the clipboard. Add as many as you like.
Check the settings
MP4 is already selected. Keep the original resolution or pick a smaller one, and choose a quality.
Download your MP4 videos
Each file gets its own download button as soon as it's ready. Download all saves everything in one ZIP file.
The formats
AVI and MP4 at a glance
What is an AVI file?
AVI is a video format Microsoft introduced in 1992. It can hold many codecs, often DivX, Xvid, or MJPEG, and files are usually larger than a modern MP4 of the same quality. Old cameras, webcams, and Windows software still produce it, but phones, Macs, and websites often can't play it. It opens in VLC, Windows Media Player, mpv, and most video editors. QuickTime, iPhone, and many websites can't play most AVI files.
What is an MP4 file?
MP4 is the most widely supported video format. It usually holds H.264 video with AAC audio, a combination that plays on practically every phone, computer, TV, and website. It balances quality and file size well, which is why most cameras, phones, and editors export to it. It opens in everything: Windows Media Player and Films & TV, QuickTime and Photos on Mac, iPhone, Android, smart TVs, VLC, and every major website and video editor.
Good to know
What changes when you convert AVI to MP4
- If the video and audio already use codecs that MP4 supports, they're copied without re-encoding, which is lossless and fast. Otherwise the video is converted to H.264 video with AAC audio.
- Only the main video and audio tracks are kept. Subtitles, chapters, and extra audio tracks aren't carried over.
- AVI files are converted with FFmpeg running in your browser. It's slower than a desktop app, so a long HD video can take several minutes.
- The first conversion downloads FFmpeg compiled to WebAssembly (10 MB). It's cached, so later visits start quickly.
- Copy-protected (DRM) files can't be converted.
- Very long videos can run out of memory, especially on phones.
FAQ
Questions, answered
Why does AVI to MP4 need a one-time download?
AVI files can contain many older codecs that browser media APIs cannot decode. A WebAssembly build of FFmpeg handles those codecs locally and is cached for later conversions.
Is this AVI to MP4 converter free?
Yes. It's completely free, with no sign-up, no watermark, and no limit on how many files you convert. It costs Ethical Tube nothing to run, because the conversion happens on your own device rather than on a server.
Are my files uploaded anywhere?
No. The conversion runs inside your browser with FFmpeg compiled to WebAssembly, so your files never leave your device. Once the page and the engine have loaded, it even works offline.
Does converting AVI to MP4 lose quality?
Not if the codecs already fit: then the video and audio are copied as they are, with no loss. When they have to be re-encoded, the default quality keeps the result visually close to the original. Pick a higher quality for footage you plan to edit.
How long does it take?
When the video can be copied without re-encoding, a few seconds. Otherwise it depends on the video's length and resolution and on your device. With a hardware encoder, a 10-minute 1080p video usually takes a few minutes on a laptop.
Can I convert several AVI files at once?
Yes. Add as many as you like. They're converted one after another, and you can download each MP4 file as soon as it's ready or all of them in one ZIP file.
Does it work on iPhone, Android, Mac, and Windows?
Yes, in any current browser on a computer or phone. FFmpeg runs on your processor without hardware acceleration, so long videos are much faster on a computer.
What can open an MP4 file?
Everything: Windows Media Player and Films & TV, QuickTime and Photos on Mac, iPhone, Android, smart TVs, VLC, and every major website and video editor.
Is there a file size limit?
There's no upload limit because nothing is uploaded. The practical limit is your device's memory: everyday files are fine, and a computer can usually handle videos up to about 2 GB.
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