Convert AVI to MP4

Convert AVI to MP4 online. Old DivX, Xvid, MJPEG and DV videos become a smaller H.264 MP4 that plays on phones, TVs and editors. No upload.

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Why convert AVI to MP4?

MP4 is the most widely supported video format. Converting from AVI fixes "unsupported file" errors on phones, social sites, presentation apps and video editors.

How the conversion works

The AVI video is decoded and re-encoded to H.264 with AAC audio. That combination plays on nearly every phone, browser, TV and editor.

What is an AVI file?

AVI, Audio Video Interleave, is a container Microsoft introduced in 1992. It was the standard for home video on Windows for years, so old camcorder captures, digital camera clips, DivX and Xvid downloads and screen recordings from the 2000s often come as .avi. Phones, iPads, Macs and most web services no longer play the codecs inside.

How to convert AVI to MP4

Drop the .avi files above and press Convert all. Browsers can't read AVI on their own, so the tool loads FFmpeg compiled to WebAssembly, decodes the old video codec and encodes H.264 at CRF 23 with AAC audio at 160 kbps. The first conversion downloads the engine, and later ones start faster. The MP4 is written with fast start, so it begins playing straight away when streamed.

Smaller files from old video

H.264 compresses far better than the MJPEG and DV codecs many old cameras used, so a converted file is often a fraction of the size. DivX and Xvid files shrink less, since they were already compressed. Interlaced camcorder footage keeps its interlacing, which can show combing lines on fast motion.

Encoding happens on your device

Video encoding runs in this browser tab, on your own device. There is no upload and no queue. Your device does all the work, so a large or long clip can take a minute or more.

Before you start

Input: AVI. Output: MP4. The settings appear before anything runs, so you can check them first. Your original file is never changed.

Video work uses a lot of memory and CPU. Try a short clip first and check that the sound and playback work. On a phone, split large batches into smaller ones.

Keep the original until you have opened and checked the result. The work happens in this browser tab, so the size you can handle depends on your device's memory, your browser and the file itself.