AVI to MP4 Converter – Free Online

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AVI

How to Convert AVI to MP4 Online

Upload your AVI file

Drag and drop your .avi file onto the page or click to browse. You can select several AVI files at once to batch-convert them.

MP4 is preselected

The output format is already set to MP4, so you can convert immediately. If you need to, adjust the codec, resolution, frame rate or bitrate in the settings panel first.

Convert and download

Click Convert. The MP4 file is processed on your own device; nothing is uploaded to a server. When it finishes, click Download to save it (or Download all to get a batch as a ZIP).

Why Convert AVI to MP4?

AVI files from camcorders, DVD rips and early digital cameras are bulky and rarely play on modern phones or TVs. Converting AVI to MP4 with H.264 shrinks them dramatically while making them compatible with every current device and streaming service.

The converter re-encodes the video in your browser at the resolution and bitrate you choose, so you can also downscale a 4:3 standard-definition AVI or keep it exactly as it is.

Private by design: your AVI file is converted on your own device and never uploaded.
MP4 preselected: the output format is already chosen, so it is a one-click conversion.
Batch friendly: convert several AVI files in one go and download them as a ZIP.
No limits, no watermark: free for files of any size, with nothing stamped on the output.

AVI vs MP4

AVI (Audio Video Interleave): AVI (Audio Video Interleave) is Microsoft's classic container from the early Windows era. It is still recognised by almost every Windows program and older media player, though its files tend to be large. It is best for legacy Windows software and older hardware players.

MP4 (MPEG-4 Part 14): MP4 is the most widely supported video container in the world. It usually carries H.264 or H.265 video with AAC audio, plays on every phone, browser, TV and editing app, and is the safest choice for sharing. It is best for sharing, social media, web playback and mobile devices.

In short: keep AVI when the priority is legacy Windows software and older hardware players, and switch to MP4 when the file is headed for sharing, social media, web playback and mobile devices. Need a different target? The full Video Converter supports every format listed below.

AVI to MP4 FAQ

Will my DivX or Xvid AVI convert?

Yes. AVI files are decoded with FFmpeg running in your browser, which handles DivX and Xvid (MPEG-4 Part 2) as well as H.264, MJPEG and DV, and re-encodes the video to H.264 for the MP4.

How much smaller will the MP4 be?

Typically 40 to 70% smaller at the same visual quality, because H.264 is far more efficient than the codecs used in most AVI files.

Is this AVI to MP4 converter free?

Yes. Converting AVI to MP4 on MediaConverter.io is completely free, with no watermark, no sign-up and no daily conversion limit.

Are my AVI files uploaded to a server?

No. The converter runs inside your browser using WebAssembly and WebCodecs, so your .avi file is read and converted on your own device. Nothing is uploaded, which keeps private recordings private and means there is no waiting in an upload queue.

Is there a file size limit for AVI to MP4?

No fixed limit. Because processing happens locally, the practical limit is your computer's memory and patience; multi-gigabyte AVI files convert fine on a desktop browser. Very large files take longer on phones.

Will converting AVI to MP4 reduce quality?

The video is re-encoded into MP4. Keep the source codec, resolution and bitrate (the defaults) and the result is visually the same as your AVI; lowering the bitrate or resolution is what reduces quality, and you control that trade-off in the settings panel.

Which browsers support the AVI to MP4 converter?

Current versions of Chrome, Edge, Firefox and Safari on desktop all work. Chrome and Edge are fastest because they expose hardware-accelerated WebCodecs decoders.