MP4 vs WebM vs MKV: Which Video Format to Use

MP4, WebM and MKV are containers: boxes that hold video and audio streams. The quality is decided by the codec inside (H.264, VP9, AV1...), but the container decides compatibility.

MP4 — the universal default

Plays on phones, TVs, browsers, editing software, messengers. If you need one format to send to an unknown device, it is MP4 with H.264. Convert MOV to MP4, AVI to MP4 or MKV to MP4 and stop worrying.

WebM — built for the web

An open container from Google holding VP9 or AV1 video. Better compression than H.264-MP4, native to browsers and HTML5, and royalty-free. Weak spots: hardware players and Apple devices historically lag behind. Use MP4 to WebM for website videos.

MKV — the archivist's container

Matroska holds practically anything: multiple audio tracks, subtitles, chapters, any codec. Perfect for storing movies. Terrible for sharing, because many devices and apps cannot open it. The fix is a quick MKV to MP4 conversion.

What about MOV and AVI?

MOV is Apple's container, near-identical to MP4 internally; cameras and iPhones produce it. AVI is a 1992 legacy format with poor codec support and big files; the only reason to keep one is software that demands it. Both are usually best converted to MP4.

Bottom line

• Send to anyone / play anywhere → MP4
• Embed on your website → WebM
• Long-term storage with subtitles and tracks → MKV