Convert WebM to MP4

Convert a WebM recording into an H.264 MP4 that plays on iPhone, Windows, Mac and every video editor. The conversion runs in your browser, so nothing is uploaded.

Your file never leaves your device. How?

Your media is processed in your browser and is not uploaded to our servers for conversion. Page assets (including the converter engine) still load over the network.

Select or drop a video to convert to MP4

MOV, WebM, MKV, AVI, M4V and more. Converted on your device.

Click, tap, or drop a file

How to convert WebM to MP4

Choose the WebM

Drop or select the .webm file.

Keep Maximum compatibility

It's preselected because WebM's VP9 video and Opus audio need re-encoding to play everywhere.

Convert

The video is re-encoded to H.264 on your device. Longer videos take a few minutes.

Download

Play the MP4 in the page, then download it.

Why WebM files need re-encoding

Browsers record in WebM. Screen recorders built into websites, many meeting and interview tools, and videos saved from web pages often come out as .webm, with VP8 or VP9 video and Opus or Vorbis audio.

iPhones, QuickTime, Premiere, iMovie, WhatsApp and many upload forms don't handle those codecs well. Renaming or rewrapping the file isn't enough; the video has to be re-encoded to H.264 and the audio to AAC, which is what Maximum compatibility does. Because re-encoding happens in your browser, it works for videos up to 120 MB and 10 minutes on a computer.

What happens to your WebM

FFmpeg in WebAssembly decodes the VP8 or VP9 video and re-encodes it with x264 at a quality setting that is visually close to the original. The Opus or Vorbis audio is re-encoded to AAC at 160 kbps.

Browser recordings are often variable frame rate and sometimes lack a duration in the file header. The converter handles both, though the progress bar may be less precise for such files.

Features

H.264 + AAC output

The most widely supported video format, accepted by phones, editors and upload forms.

Handles browser recordings

Works with files from web-based screen and meeting recorders.

Near-original quality

Encoded at a quality level that is hard to tell apart from the source.

Private

Meeting and screen recordings never leave your device.

Frequently asked questions

Is my video uploaded?

No. The conversion runs in your browser with a WebAssembly build of FFmpeg. The video is read from your device and the MP4 is saved back to it.

Why won't my WebM play on iPhone or in Premiere?

WebM uses VP8/VP9 video and Opus/Vorbis audio, which Apple apps and many editors don't support. Converting to H.264 MP4 fixes it.

Can I use Fast mode for WebM?

You can, but it keeps the VP9 and Opus streams, so the MP4 still won't play in many places. Maximum compatibility is the right choice for WebM.

How large a video can I convert?

Fast mode handles up to 500 MB on a computer and 250 MB on a phone. Maximum compatibility re-encodes every frame in the browser, so it is limited to 120 MB and 10 minutes on a computer, or 60 MB and 5 minutes on a phone. Trim longer videos first.

Does converting lose quality?

Re-encoding always changes the video slightly, but the quality setting used is visually close to the original for screen recordings and camera footage.

I only need the audio. Is there a faster way?

Yes. WebM to MP3 converts only the audio, which is much faster and has higher size limits.