AVI to MP4 Converter – Free Online

How to Convert AVI to MP4 Online

Drop your AVI file

Drag and drop your .avi file onto the box above, or click Choose Files. The request is already filled in: “Convert this to MP4”.

Say how, if you want

The AI assistant uses sensible defaults. To choose the resolution, frame rate or bitrate yourself, say so in the request, for example “Convert this to MP4 in 720p”.

Save your MP4 file

The assistant opens with your file and converts it on your own device; the file itself is never uploaded. When the MP4 file is ready, click Save. Prefer to set everything by hand, or batch-convert several files into a ZIP? The classic converter is one click away on this page.

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 video is re-encoded in your browser at the resolution and bitrate you ask for, so you can also downscale a 4:3 standard-definition AVI or keep its original size.

Private by design: your AVI file is converted on your own device and never uploaded.
MP4 already asked for: the AI assistant's request says MP4, so one drop does it. Want a particular resolution, frame rate or bitrate? Just say so.
Batch friendly: the classic converter on this page takes several AVI files in one go and downloads them as a ZIP.
Free, no watermark: no sign-up, and 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 read with FFmpeg running in your browser, which handles DivX and Xvid (MPEG-4 Part 2) as well as H.264, MJPEG and DV. The video is re-encoded to H.264 for the MP4, an H.264 AVI included: an AVI keeps its frame times in decoding order, so a copy of its H.264 could play frames out of order.

How much smaller will the MP4 be?

For a DivX, Xvid, MJPEG or DV AVI, often 40 to 70% smaller at a similar visual quality, because H.264 is far more efficient than those codecs. An AVI that already holds H.264 is re-encoded too, so it comes out about the same size, sometimes larger.

Is this AVI to MP4 converter free?

Yes. Converting AVI to MP4 on MediaConverter.io is free, with no watermark and no sign-up. The AI assistant runs on a free daily allowance of assistant credits; the classic converter on this page has no daily limit at all.

Are my AVI files uploaded to a server?

No. The conversion runs inside your browser using FFmpeg compiled to WebAssembly, so your .avi file is read and converted on your own device and never uploaded, which keeps private recordings private and means there is no waiting in an upload queue. The AI assistant only sees what you type and basic facts about the file: its name, format, duration and size.

Is there a file size limit for AVI to MP4?

There is no plan or account limit, but the converter loads the whole AVI file into your browser's memory, so about 2 GB per file is the practical ceiling; larger files may fail to open. Most AVI files hold DivX, Xvid or MJPEG video, which browsers cannot decode, so this conversion runs entirely in FFmpeg on your CPU, without the browser's hardware video decoders, and large files take noticeably longer.

Can I choose the MP4 settings myself?

Yes. Ask the AI assistant for a resolution, frame rate or bitrate in your request. Audio and subtitle track selection, the codec list and every other setting are in the classic converter, one click away on this page.

Will converting AVI to MP4 reduce quality?

FFmpeg re-encodes the video into MP4 at a standard quality setting in 8-bit 4:2:0 color, so even at the default resolution and bitrate it is not a bit-for-bit copy: an ordinary 8-bit video looks much the same as your AVI, while a 10-bit, HDR or full-color (4:2:2 or 4:4:4) source loses some color detail. Lowering the bitrate or resolution reduces quality further, and you control that trade-off by asking for it (or in the classic converter's settings).

Which browsers support the AVI to MP4 converter?

It is built and tested on current desktop Chrome and Edge. The conversion itself runs in WebAssembly, which every current desktop browser supports, so speed depends mostly on your computer's processor.