01
Modern compression standards
WEBM typically achieves better compression efficiency than MP4 at equivalent perceived quality. The result is a smaller file that still looks or sounds the same to most listeners and viewers.
100% local
VIDEO
Convert MP4
to WEBM
Modern compression standards.
WEBM typically achieves better compression efficiency than MP4 at equivalent perceived quality. The result is a smaller file that still looks or sounds the same to most listeners and viewers.
— Drop area
WHY CONVERT
Why convert MP4 to WEBM
02
Broader cross-platform support
WEBM is accepted by a wider range of video players, mobile devices, and streaming platforms than MP4. The conversion removes a recurring compatibility friction without changing what the file actually contains.
03
Lower storage and bandwidth cost
WEBM files are typically smaller than their MP4 counterparts, which reduces hosting, transfer, and storage costs at scale. The savings compound when serving the same content to many recipients.
— How to convert
MP4 to WEBM in three steps.
- 01
Open LocalConvert
Visit this page on any modern browser — no install, no signup, no plugin.
- 02
Drop or select your MP4 file
Drag your MP4 into the drop area, or click to pick one from your device.
- 03
Click Convert
Conversion runs entirely in your browser. When it's done, your WEBM file downloads to your device.
QUALITY & FIDELITY
Quality and fidelity
- Full video and audio re-encode (H.264/AAC → VP9/Opus) — second-generation lossy artifacts.
- WebM does not play in Safari on older macOS/iOS versions.
- Most container-level metadata is preserved.
Transparency MP4
✗ WEBM
✓
Color depth 8/10-bit video, AAC audio 8/10-bit video, Opus/Vorbis audio
Metadata preserved ✓
FORMAT SPECS
Format specifications
| MP4 | WEBM | |
|---|---|---|
| Extensions | .mp4 .m4v | .webm |
| MIME types | video/mp4 | video/webm |
| Introduced | 2001 | 2010 |
| Maintainer | ISO/IEC (MPEG-4) | Google / WebM Project |
| Magic # | 00 00 00 ?? 66 74 79 70 | 1A 45 DF A3 |
| Spec | View spec ↗ | View spec ↗ |
COMPATIBILITY
Where these formats work
| Platform | Windows | macOS | iOS | Android | Chrome | Firefox | Safari | Edge |
|---|---|---|---|---|---|---|---|---|
| MP4 | Native | Native | Native | Native | Native | Native | Native | Native |
| WEBM | App | App | App | Native | Native | Native | Native | Native |
MP4
- Windows
- Native
- macOS
- Native
- iOS
- Native
- Android
- Native
- Chrome
- Native
- Firefox
- Native
- Safari
- Native
- Edge
- Native
WEBM
- Windows
- App
- macOS
- App
- iOS
- App
- Android
- Native
- Chrome
- Native
- Firefox
- Native
- Safari
- Native
- Edge
- Native
Why LocalConvert
How LocalConvert compares
| Category | LocalConvert | Cloud converters |
|---|---|---|
| PRIVACY | Files never leave your device. The whole pipeline runs in your browser via WebAssembly. | Files travel to a remote server, sit in queue storage, and may be retained for analytics or moderation. |
| COST | Free, no signup, no daily quotas. | Often free for small files; paid tiers for batch / large / commercial use. |
| LIMITS | Limited only by your device's memory and CPU. Multi-GB raw footage OK on desktop. | Typical 100 MB to 1 GB per-file caps, plus rate limits. |
— The formats
From · MP4
MPEG-4 Part 14
The most widely supported video container. Pairs efficient compression with broad device compatibility.
Typical uses
Streaming, social media uploads, recording, sharing.
To · WEBM
Web Media
An open, royalty-free video container designed for the web. Often paired with VP9 or AV1 codecs.
Typical uses
Web video, screen recordings, HTML5 playback.
— FAQ
Frequently asked.
Is MP4 to WEBM conversion free?
Yes. LocalConvert is completely free, with no signup and no per-file or per-day limits.
Do my files get uploaded anywhere?
No. MP4 to WEBM conversion happens entirely inside your browser using WebAssembly — your file never leaves your device.
What's the maximum file size?
There's no fixed cap — the practical limit is your device's available memory. Very large files may take longer or fail on low-RAM devices.
Does it work offline?
Yes — once the page has loaded, MP4 to WEBM conversion works without an internet connection. Re-open the page once to cache it.
Will conversion preserve quality?
LocalConvert uses the industry-standard tools (FFmpeg, ImageMagick, Pandoc) — quality matches what professionals use on the command line. Lossy formats will still lose some quality on each re-encode.
— Related
Or convert these.
Browse all conversionsREFERENCES
Format references
Last verified:
100% local conversion.
MP4 to WEBM is processed in your browser with WebAssembly. No upload, no tracking, no limits. Your file never leaves your device.