WebM to MP4 Converter
Re-encodes VP8 or VP9 to H.264 so iPhones, TVs and editors accept it.
Up to 50 MB per file. Sign up free to convert files up to 100 MB.
| File name | Size | Convert to |
|---|
Checking files and selected output formats.
What to expect when converting WEBM to MP4
Measured on 720p clips: a high-bitrate WebM (VP9 CRF 18) came out 42% smaller (7.64 MB to 4.41 MB), while a heavily compressed one (VP9 CRF 45) more than doubled (1.71 MB to 3.49 MB). Typical web downloads landed 7-15% smaller.
Quality: Re-encoded from VP8/VP9 to H.264 at a fixed quality target, with audio re-encoded to AAC at 192 kbps. One generation of loss, generally invisible on normal footage.
Heads up: MP4 doesn't support transparency, so transparent backgrounds in your WEBM will be flattened (usually to white).
Best for: devices that don't support WebM (older iOS, smart TVs, video editing software).
Avoid when: web embedding, WebM is more efficient and widely supported in browsers.
Tip: The output size is set by our encoder's quality target, not by the size of the file you upload. That is why an already-squeezed WebM gets bigger while a high-bitrate one gets smaller, the MP4 is encoded to a consistent quality either way.
WebM to MP4: maximum device compatibility
WebM's VP8/VP9 codecs have strong browser support but limited device support, many smart TVs, game consoles, and older mobile devices cannot play WebM natively. MP4 with H.264 plays on virtually every device manufactured in the last 15 years. The conversion decodes the VP8/VP9 video and Vorbis/Opus audio, then re-encodes with H.264 video and AAC audio. If the WebM uses VP9, the re-encode to H.264 may increase file size by 10-20% at equivalent quality.
Convert WebM to MP4 when sharing video with people on mobile devices, uploading to social media platforms, sending via email or messaging apps, or playing on smart TVs and media players. MP4 is the universal video format.
WebM vs MP4: Side-by-side
Technical comparison of the two formats, useful for deciding which to use, or for confirming what changes during conversion.
| Property | WebM | MP4 |
|---|---|---|
| Full name | WebM (Google) | MPEG-4 Part 14 |
| Year introduced | 2010 | 2001 |
| Developer / standard body | MPEG | |
| MIME type | video/webm | video/mp4 |
| File extension | .webm | .mp4 / .m4v |
| Compression | VP8/VP9/AV1 video + Vorbis/Opus audio | H.264 or H.265 codec |
| Color / data depth | 8/10/12-bit | 8/10-bit |
| Max dimensions / size | Codec-dependent | Codec-dependent (up to 8K) |
| Transparency | Yes | No |
| Animation | No | No |
| Standard / specification | Open Web Foundation | ISO/IEC 14496-14 |
| Best for | Web-native video, HTML5 <video> tag | Universal video compatibility, plays on every device |
Use WebM when
- You control the modern-browser environment and page-weight matters
- You want to avoid patent-encumbered codecs
- You're serving HTML5 video where smaller files improve UX
- Your CDN can serve WebM alongside MP4 automatically
Use MP4 when
- You need universal playback on any device, ever
- You're uploading somewhere that expects MP4
- Older browsers or embedded devices are in your audience
- You want a safe single-format delivery
For a modern site where you control the audience, WebM saves bandwidth and licensing hassle. For anywhere else, MP4 remains the safe bet. If you're running video on a public website, offering both in an HTML5 picture-style pair is a common solution, browsers pick the smaller one they can play automatically.