AVI to MP4 Converter

AUTO-DELETE/Files are processed on our server and deleted as soon as conversion finishes.

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How to Convert AVI to MP4 Online

AVI to MP4: what changes in the file

This tool takes a AVI file, processes it with FFmpeg on DownloadVideo.vn servers and returns a MP4 file.

Both AVI and MP4 are lossy, so converting adds another generation of compression: a small further loss that is usually hard to notice after one conversion.

How AVI and MP4 differ

Property	AVI	MP4
Full name	Audio Video Interleave	MPEG-4 Part 14
Introduced	Microsoft, 1992	ISO/IEC MPEG, 2003
Compression	lossy	lossy
Common codecs	MPEG-4 Part 2 (DivX/Xvid), MJPEG, MP3	H.264, H.265/HEVC, AV1, AAC
Strengths	opens in almost every desktop player and older editing software	plays on virtually every phone, browser, TV and editor; standard upload format for YouTube, TikTok, Facebook, Instagram
Limitations	old design: large files for the same quality; no native playback in web browsers or most phones	lossy codecs: every re-encode loses a little quality

Measured with a sample file

On September 25, 2026 we ran the tool on our production server with a sample file: a 10-second 1280×720 video (MPEG-4 Part 2 + MP3), 9.2 MB.

Result: 9.2 MB → 3.5 MB, processed in 9.1 s. Output: H.264 video at 1280×720, AAC audio at 44.1 kHz stereo, 128 kbps.

Real sizes depend on your content (how complex the picture and sound are, and the length); the figures only show the order of change.

Before you convert

The tool always re-encodes the picture and sound, even when the source codec would already fit the target format.
Up to 500 MB per file; a conversion that runs longer than 10 minutes is cancelled.
The file is sent to our server for conversion and deleted as soon as processing ends, including when it fails.

Frequently asked questions

Does converting AVI to MP4 reduce quality?

Slightly: it is a second round of lossy compression. One conversion is usually hard to notice, but repeated conversions add up.

How does the file size change from AVI to MP4?

With our sample file: 9.2 MB → 3.5 MB. Your file may differ depending on its content.