---
title: "WebM to MP4 Converter for Browser Recordings | ToolSugar"
description: "Convert WebM screen recordings and web downloads to MP4 in your browser. VP8, VP9 and Opus are re-encoded to H.264 and AAC on your device, with no upload."
canonical: https://toolsugar.com/tools/webm-to-mp4
image: https://toolsugar.com/og.png
---

# Convert WebM to MP4

Choose a WebM file and the tool re-encodes it to H.264 video and AAC audio inside your browser. WebM almost always holds VP8 or VP9 video with Opus audio, which MP4 players do not read, so copying is rarely possible. Expect it to take some time, and keep the tab open until it finishes.

Runs on your device

## How it works

1. Choose a WebM file from your device.
2. Press Convert to MP4. The method can stay on Copy when possible.
3. Keep the tab open while the frames are re-encoded.
4. Check the preview and download the MP4.

## Key facts

- **Typical input**: VP8 or VP9 video with Opus audio
- **Output**: H.264 video and AAC audio in MP4
- **File limit**: 120 MB on a computer, 60 MB on a phone
- **Encoding speed**: A minute of 1080p at 30 fps took about 8 seconds on an Apple M4 Pro laptop using its video hardware, and 2 to 4 minutes on the fallback engine. Phones and older computers take longer.
- **First run**: Some jobs download a 32 MB video engine once, then your browser reuses it
- **Your file**: Processed inside this tab and never uploaded

## Common uses

- Share a browser screen recording with someone on an iPhone.
- Add a recorded meeting or demo to a slide deck.
- Bring a WebM download into an editor that needs MP4.
- Attach a Loom style recording to a support ticket.

## Questions

### Why does WebM take longer than other formats?

MOV and MKV files often already hold H.264, so they can be copied. WebM holds codecs that MP4 players do not read, so every frame has to be decoded and encoded again. That uses your device's video hardware when the browser supports it, and one CPU thread when it does not.

### My recording shows no length or a wrong one. Will it still convert?

Yes. Browser recorders often leave the length out of the file. The output MP4 gets a correct length, but the progress bar cannot show a percentage during the conversion, so the spinner is the only sign of progress.

### Will the odd sized screen recording work in MP4?

Yes. H.264 needs even pixel dimensions, and a screen capture often has odd ones. If a side is an odd number, the tool trims one pixel so the result plays everywhere.

### Is my video uploaded anywhere?

No. The video engine runs inside your browser tab and reads the file from your device. ToolSugar's servers never receive it, and closing the tab clears the working copy from memory.

[Read the WebM to MP4 guide](https://toolsugar.com/blog/how-to-convert-a-video-to-mp4)

## Related tools

- [Convert to MP4](https://toolsugar.com/tools/video-converter)
- [Compress Video](https://toolsugar.com/tools/video-compressor)
- [Trim Video](https://toolsugar.com/tools/video-trimmer)
- [MOV to MP4](https://toolsugar.com/tools/mov-to-mp4)