Video Format Comparison

MP4 vs WebM: Which Video Format for the Web?

For web video, MP4 with H.264 has been the dominant format since HTML5 video became standard. WebM was created by Google in 2010 as an open-source, royalty-free alternative. Both work in modern browsers, but MP4 has broader support — particularly on iOS and older Safari. For production-level web video: use MP4 as your primary format and optionally serve WebM to browsers that support it for better compression.

MP4vsWebM

Quick Verdict

Use MP4 when…

Use MP4 for maximum compatibility — iOS, Safari, and all major platforms accept MP4. It's the safest choice for web video when you want zero compatibility surprises.

Use WebM when…

Use WebM as a supplemental format alongside MP4 for open-source or Google-ecosystem projects. WebM with VP9 or AV1 can be noticeably smaller than H.264 MP4 at equivalent quality.

MP4 vs WebM: Feature Comparison

Feature	MP4	WebM
Container developer	MPEG group — industry standard	Google — open-source alternative
Video codec	H.264 or H.265 (most common)	VP8, VP9, or AV1 (open-source, royalty-free)
Audio codec	AAC (most common)	Vorbis or Opus
iOS / Safari support	Full native support	Limited — Safari added VP9 support in 2020, AV1 in 2023+
Chrome support	Full	Full — Chrome is Google's browser, best WebM support
File size at equivalent quality	Baseline (H.264)	VP9: ~20% smaller. AV1: ~50% smaller than H.264
Licensing	H.264: patent-encumbered	VP9 and AV1: completely royalty-free

When MP4 wins

✓Container developer: MPEG group — industry standard
✓Video codec: H.264 or H.265 (most common)
✓Audio codec: AAC (most common)

When WebM wins

✓Container developer: Google — open-source alternative
✓Video codec: VP8, VP9, or AV1 (open-source, royalty-free)
✓Audio codec: Vorbis or Opus

Frequently asked questions

Does Safari support WebM?

Safari added partial WebM support over time. VP9 in WebM was added in Safari 14.1 (macOS 11.3, iOS 14.5, 2021). AV1 support is available in Safari 17 (macOS 14 Sonoma, iOS 17, 2023) but only on hardware with AV1 decode support. For maximum compatibility including older Safari versions: always include an MP4 H.264 fallback.

How do I serve both MP4 and WebM for web video?

Use the HTML5 <video> element with multiple <source> elements: <video><source src='video.webm' type='video/webm'><source src='video.mp4' type='video/mp4'></video>. Browsers pick the first format they support — WebM-capable browsers use WebM; others fall back to MP4.

Is WebM smaller than MP4?

WebM with VP9 is typically 20–30% smaller than MP4 with H.264 at equivalent quality. WebM with AV1 is ~50% smaller. However, encoding VP9 takes longer than H.264, and AV1 is significantly more CPU-intensive to encode. For a personal website with a few videos: MP4 H.264 is simpler and the size difference is negligible. For a high-traffic streaming service: WebM/AV1 bandwidth savings are meaningful.