How to convert WebM to MP4
- 1
Drop your WebM file into the converter above, or click to browse. Nothing is uploaded — the file stays on your device.
- 2
Adjust the settings (quality, resolution, and trim). Tip: For screen recordings, quality 75–85 keeps text crisp while keeping the file small.
- 3
Click “Convert to MP4”. The conversion runs locally in your browser — larger files take longer, and a progress bar keeps you posted.
- 4
Preview the result and hit Download to save your MP4 file.
Why convert WebM to MP4?
WebM is the web's open video format, and it's what Chrome extensions, Loom-style recorders, and many capture tools produce by default. The problem starts when you try to use that recording anywhere else: Premiere Pro, iMovie, Final Cut, iPhones, and PowerPoint all handle WebM poorly or not at all.
MP4 solves this instantly — it's accepted by every editor, device, and platform. This converter re-encodes the VP8/VP9 video to H.264 and the Opus/Vorbis audio to AAC, producing a standard MP4 that works everywhere.
WebM vs MP4 at a glance
| WebM | MP4 | |
|---|---|---|
| Type | Video container (VP8/VP9 + Opus) | Video container (H.264 + AAC) |
| Compression | Lossy, efficient, royalty-free | Lossy, very efficient |
| Audio | Yes (Opus/Vorbis) | Yes (AAC) |
| Compatibility | All modern browsers; weak in editors and on Apple devices | Universal — every device, browser, and editor |
| Best for | Web embeds, HTML5 video, screen recordings | Sharing, social media, editing, playback anywhere |
About the formats
WebM WebM (VP8/VP9 + Opus)
WebM is the open, royalty-free video format built for the web, using the VP8/VP9 codecs with Opus or Vorbis audio. Browsers and screen recorders love it — Chrome extensions and many capture tools export WebM by default — but desktop editors, iPhones, and smart TVs often refuse to open it.
MP4 MPEG-4 Part 14
MP4 is the most widely supported video format in the world. Built on the H.264 codec with AAC audio, it plays on every phone, browser, TV, and editing app, and offers an excellent balance of quality and file size. When in doubt, MP4 is the safe choice for sharing video.
Frequently asked questions
Why won't my WebM file open in Premiere or iMovie?
Most desktop editors don't license the VP8/VP9 decoders WebM uses, so they either reject the file or import it without audio. Converting to MP4 (H.264 + AAC) makes the footage editable in any editor.
Does the audio convert too?
Yes — WebM audio (Opus or Vorbis) is automatically converted to AAC, the standard MP4 audio codec, and stays in sync with the video.
Is this WebM to MP4 converter really free?
Yes — completely free, with no watermarks, no sign-up, and no conversion limits. The tool is supported by ads on this page, so the converter itself never asks you for anything.
Are my files uploaded to a server?
No. This converter runs entirely in your browser using WebAssembly (a browser build of FFmpeg). Your WebM file never leaves your device — nothing is uploaded, stored, or seen by us, which also makes it safe for private or confidential files.
Is there a file size limit?
There's no hard limit. Because conversion happens on your own device, the practical ceiling is your browser's memory — files up to a few hundred megabytes work well on most computers. Very large files may be slow or fail on low-memory devices.
Why does the first conversion take a moment to start?
The first time you convert, your browser downloads the conversion engine (about 31 MB) once. It's cached after that, so later conversions start instantly — and they keep working even offline.
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