How to Convert WebM to MP4
- Add your video — Drag and drop a WebM file into the upload area, or click "browse files" to select one from your computer.
- Wait for conversion — The converter engine loads automatically (about 31MB on first use, cached for future visits). Your video converts right in your browser.
- Download — Click "Download MP4" to save the converted file. The original quality is preserved.
What is a WebM File?
WebM is an open video format developed by Google, designed specifically for the web. It uses VP8 or VP9 video codecs paired with Vorbis or Opus audio. WebM is the default format for many YouTube video downloads, screen recordings made in Chrome, and HTML5 video on websites. While it's great for web use, WebM has limited support outside of browsers.
Why Convert WebM to MP4?
WebM files don't play on iPhones, iPads, or most media players and smart TVs. If you've downloaded a video from a website or recorded your screen and the file won't play on your phone or TV, it's probably a WebM file. MP4 is the universal video format that works on every device — iOS, Android, Windows, Mac, smart TVs, game consoles, and every web browser. Converting WebM to MP4 ensures your video plays everywhere without compatibility issues.
Is the Quality Preserved?
Yes. When the video codec is already MP4-compatible, the converter remuxes the file — meaning it copies the video and audio streams directly without re-encoding. This is fast and produces an identical-quality output. If re-encoding is needed (common with VP8/VP9 codecs), the converter uses high-quality settings to minimize any quality loss.
Supported Input Formats
.webm
Supports WebM files with VP8, VP9, and AV1 video codecs and Vorbis or Opus audio codecs. The converter handles all common WebM configurations from YouTube downloads, screen recordings, and web captures.
Frequently Asked Questions
Is this WebM to MP4 converter free?
Yes, completely free. No sign-up, no hidden fees, no watermarks. Convert as many videos as you need.
Are my videos uploaded to a server?
No. All processing happens locally in your browser using WebAssembly (ffmpeg.wasm). Your files never leave your device. We never see, store, or have access to your files.
How long does the conversion take?
The first time you use the tool, it downloads the converter engine (~31MB). This is cached by your browser for future visits. The actual conversion time depends on your file size and device — most files under 200MB convert in under a minute.
Is there a file size limit?
There's no hard limit, but since conversion happens in your browser's memory, very large files (over 500MB) may be slow or cause issues. For best results, keep files under 500MB.
Will the video quality be the same?
Yes. The converter remuxes (directly copies) the video and audio streams when possible, preserving the original quality. If the codecs need to be changed, it uses high-quality encoding settings.
What devices does this work on?
This converter works on any device with a modern web browser — Windows, Mac, Chromebook, and Linux. Mobile devices may have limited memory for large files. No software to install.
What is a WebM file?
WebM is an open video format created by Google for the web. It's commonly used for YouTube downloads, browser-based screen recordings, and HTML5 video. While it works great in web browsers, most phones, TVs, and media players don't support it. Converting to MP4 ensures your video plays on any device.