Guide · Video

MP4 vs WebM: which should you use?

MP4 is the video format that plays everywhere; WebM is the open format built for the web. For a page you control, WebM can be smaller — but MP4 is the universal safe bet. Often the best answer is serve both.

Codecs & file size

MP4 usually carries H.264 (with AAC audio) — extremely well supported and hardware-accelerated on virtually every device. WebM carries VP9 or AV1 (with Opus audio), newer codecs that compress harder: at the same visual quality a WebM is often smaller than an H.264 MP4, which means faster loads and less bandwidth. The catch is that the tougher compression takes more CPU to encode.

Compatibility

MP4/H.264 is the most universally-playable video there is — every phone, browser, smart TV, editor and social platform accepts it. WebM support in modern browsers is excellent, but it's weaker outside them: some social platforms, messaging apps, older devices and editing tools won't take a WebM. If a video is going to social media or someone's phone, MP4 is the reliable choice.

Best of both on the web

For video embedded on your own site, you don't have to choose — offer both and let the browser pick the smaller one it supports:

<video controls>
  <source src="clip.webm" type="video/webm">
  <source src="clip.mp4"  type="video/mp4">
</video>

When to use which

• Use MP4 for: social media, sharing, phones, editing, and universal playback.
• Use WebM for: video embedded on a website where smaller files and open codecs help — ideally alongside an MP4 fallback.

Convert either way

Processed privately with a local ffmpeg engine, auto-deleted after an hour:

• Convert MP4 to WebM — smaller, web-tuned.
• Convert WebM to MP4 — universal, share-anywhere.

Wondering about Apple's format too? See MP4 vs MOV.

TL;DR

MP4 for reach — it plays everywhere. WebM for the web — smaller and open. On your own site, ship both with MP4 as the fallback.