WebM to MP4 Converter
Choose a WebM file and convert it to an MP4 with AVC video and AAC audio. Processing stays on your device.
More private browser video tools
Edit or convert one video without sending it to an Instasize processing server. Codec support and processing speed depend on the browser and device.
Edit video
Convert WebM video to MP4
WebM input
This route accepts .webm files. WebM commonly contains VP8 or VP9 video with Opus or Vorbis audio, but exact codec support depends on the browser.
MP4 output
The video and retained audio are re-encoded into an MP4 with AVC and AAC when the required browser codecs are available.
Preview the conversion
Check the complete result for sync, color, dimensions, and sound before using it in another app or website.
Output, privacy, and compatibility
Private processing
The selected video is read and processed in this browser with MediaBunny. This workflow does not upload the video to an Instasize processing server.
MP4 output
Completed edits download as MP4 files with AVC video and AAC audio when audio is retained. Re-encoding can change file size and visual quality.
Browser limits
Codec support, speed, and memory limits vary by browser and device. Keep the original file and review the complete result before deleting or publishing anything.
How to convert WebM to MP4?
- 1
Step 1: Choose a WebM file
Select one .webm video up to 200MB.
- 2
Step 2: Convert
Create an MP4 locally in the browser.
- 3
Step 3: Preview
Play the result and check its video and audio.
- 4
Step 4: Download
Save the MP4 without changing the source WebM.
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No. The MP4 output uses AVC video and does not preserve a transparent WebM alpha channel.
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