AVI to MP4

Convert AVI files into MP4 format for easier playback and sharing.

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Quick Tip

Select the .avi file.

About This Tool

Why use AVI to MP4?

Convert an old AVI into an MP4. The video is re-encoded to H.264 with FFmpeg's ultrafast preset, which prioritises getting the job done in a browser tab over squeezing out the last few per cent of file size — a sensible trade when the alternative is waiting several times longer for a marginally smaller file.

This is the conversion worth doing. AVI files will not play in a browser, will not upload to most platforms, and are usually much larger than they need to be. MP4 with H.264 plays on every phone, browser, TV and editing tool in current use, and the same content typically takes a fraction of the space. Anything sitting in an archive as AVI is a good candidate.

Key Benefits

H.264 video

The codec supported by every current browser, phone, TV and editing tool, which AVI's older codecs are not.

Ultrafast preset

Chosen deliberately for browser encoding — several times quicker than the slower presets, for a file only marginally larger.

Converted locally

FFmpeg runs in the tab, so home videos and archive footage are never uploaded to a conversion service.

How to use AVI to MP4

1
Select the .avi file.
2
Convert; the video is re-encoded to H.264 in an MP4 container.
3
Watch the progress bar — video encoding takes noticeably longer than audio.
4
Download the MP4 and check it plays before deleting the original.

Best use cases

Modernise old AVI recordings so they play on a phone.

Upload footage to a platform that rejects AVI.

Prepare old video for editing software that expects MP4.

Reduce the size of an archive of AVI files.

AVI to MP4 FAQs

Will the MP4 be smaller than the AVI?

Usually, and often by a lot. H.264 is far more efficient than the codecs typically found in an AVI, so the same content takes much less space.

Why the ultrafast preset?

Because this runs in a browser tab. Slower presets would take several times longer for a file only slightly smaller, which is a poor trade here.

Is any quality lost?

A little — this is a re-encode, not a repackage. At normal viewing size the difference is not visible, but keep the original if the footage is irreplaceable.

Why did my file fail to convert?

Most likely memory. A browser tab has a ceiling that a desktop encoder does not, so very large or very long files can exhaust it. Trim the file and try again.