AVI vs MP4: Size, Quality, and Compatibility

MP4 is the better choice for almost every situation. It produces smaller files, streams over the internet, works on all modern devices, and supports modern codecs like H.265. AVI is a legacy format from 1992 that still works for local playback but has no advantages over MP4 for new projects.

File Size and Compression

AVI was designed before efficient video compression existed. It uses minimal container overhead but often stores video with older codecs (DivX, Xvid) or even uncompressed streams. MP4 uses the MPEG-4 Part 14 container with H.264 or H.265 codecs, which achieve dramatically better compression. A 10-minute 1080p video might be 1.5GB as uncompressed AVI, 700MB as AVI with DivX, and 150MB as MP4 with H.264 at the same visual quality.

Codec Support

MP4 supports H.264, H.265/HEVC, VP9, AV1, and AAC audio. AVI technically supports many codecs but was designed around older ones. AVI cannot natively hold H.265 or AAC audio without workarounds. This matters because H.265 delivers the same quality as H.264 at half the file size, and AVI simply cannot take advantage of it properly.

Streaming

MP4 supports progressive download and adaptive streaming (DASH, HLS). You can start watching an MP4 file before it finishes downloading. AVI does not support streaming at all. The file must be fully downloaded before playback begins. Every major video platform (YouTube, Vimeo, social media) accepts MP4 uploads. AVI uploads often get rejected or re-encoded server-side.

Compatibility

MP4 plays on phones, tablets, computers, smart TVs, game consoles, and web browsers. AVI plays on Windows and most desktop media players (VLC, MPC-HC) but has limited mobile support. Modern iPhones and Android devices may not play AVI files without a third-party app. Web browsers do not support AVI playback at all.

When AVI Still Makes Sense

AVI is only worth using if you are working with legacy video editing software that requires it, or if you have archival footage already in AVI and do not want to re-encode. Some older surveillance camera systems also output AVI. In all other cases, convert to MP4.

Converting AVI to MP4

Our video to MP4 converter handles AVI, MOV, MKV, WebM, and other formats directly in your browser. For large AVI files, you might also want to use the video compressor to bring the file size down.

See also: MKV vs AVI, WMV vs MP4, MKV vs MP4, FLV vs MP4, MP4 vs MOV, MOV vs AVI, AVI vs MOV, and MP4 vs WebM for more format comparisons.