Are my files uploaded to a server?

No. This conversion runs inside your browser using your own device’s processing power, and the file is not uploaded. Once a tool has been used once (video, text recognition and background removal download their engine from this site the first time), it keeps working when your connection drops.

My AVI will not open anywhere — will this still read it?

Usually yes, since the decoders here cover the older codecs. If a file uses something genuinely obscure you get a clear message naming the codec rather than a silent failure.

Can I improve the quality while converting?

No. Converting cannot add detail that was never recorded; it makes the file playable, not sharper.

Convert AVI to MP4

Runs on your device · Your file never leaves your device.

AVI is a legacy container full of codecs modern devices dropped support for — DivX, Xvid, MPEG-4 Part 2. Converting to MP4 with H.264 makes an old recording playable again on a current phone or TV.

This is the practical fix for old camcorder footage and archived downloads that will no longer open anywhere.

DivX and Xvid files are usually small by today’s standards; a long DV tape capture is large and is converted in parts.

How to convert AVI to MP4

Add the AVI file — often an older recording or camera export.
Press Convert; older codecs inside AVI usually need a real re-encode to H.264.
Download the MP4.

Supported formats and limits

Input: AVI, including older DivX and Xvid content
Output: MP4 (H.264)
Speed: When it has to be re-encoded, slower than MKV or MP4: an AVI is encoded by the engine in the page, not your device’s video encoder
Why convert: AVI is rejected by most phones, editors and upload forms
Where it runs: In your browser; nothing uploaded

Not for: Perfectly preserving a very old recording — re-encoding costs a little quality, though the default settings keep it hard to see.

Why an AVI always takes the slower route

The reader that feeds your device's own video encoder does not open AVI files, so every AVI is converted by the engine built into the page, x264 compiled to WebAssembly. On a computer with several cores, a clip of a minute or more can be shared between copies of the engine, but this is still the slower of the two routes the site has; /rotate-video compares them.

Before converting, Inspect this file first shows what is inside: the length, the frame size, and the picture and sound codecs. DivX and Xvid are MPEG-4 Part 2, which the engine decodes. If the engine cannot decode the picture, conversion stops with a message that names the codec it found; a shorter clip or another device makes no difference to that. An AVI that holds H.264 is copied into the MP4 as it is instead of being encoded.

What changes in the sound and the picture

The sound in an AVI is often MP3, uncompressed PCM or AC-3. MP3 and AC-3 are copied into the MP4 untouched; PCM and anything else becomes AAC at 128 kbit/s.

The frame keeps its size, apart from one rule: H.264 needs even dimensions, so a frame with an odd width or height is scaled down by one pixel in that direction. Nothing is enlarged, so a 320×240 recording stays 320×240.

Camcorder DV and many TV captures are interlaced: each frame holds two half-pictures taken a fraction of a second apart. This tool does not deinterlace, so fast movement can show fine horizontal comb lines in the MP4.

Long tape captures

DV uses about 3.6 MB per second, roughly 13 GB an hour. An AVI over 1 GB is converted in parts; the site refuses a single selection over 16 GB, which for DV is a little over an hour of tape. A longer capture has to be saved as several shorter files before it can be converted here. The parts that come back stay separate files when together they are too large to hold as one.

Frequently asked questions

Are my files uploaded to a server?: No. This conversion runs inside your browser using your own device’s processing power, and the file is not uploaded. Once a tool has been used once (video, text recognition and background removal download their engine from this site the first time), it keeps working when your connection drops.
My AVI will not open anywhere — will this still read it?: Usually yes, since the decoders here cover the older codecs. If a file uses something genuinely obscure you get a clear message naming the codec rather than a silent failure.
Can I improve the quality while converting?: No. Converting cannot add detail that was never recorded; it makes the file playable, not sharper.