About WebM to MP4
WebM is the container browsers like, and it is what many screen recorders and web apps produce when they save a recording. Its video is usually VP8, VP9 or AV1 with Opus or Vorbis audio, a combination that plays perfectly in a current browser and poorly almost everywhere else: iPhones, older Windows machines, smart TVs and most video editors refuse it.
This converter decodes the WebM on our server and writes a standard MP4 with H.264 video and AAC audio, the pair every phone and television understands. Pick a quality preset before you start, and remember that any conversion re-encodes the picture, so the result is a fresh file rather than a copy of the original streams. The upload is deleted automatically after your download.
What this tool does
Built for WebM files
The picker accepts .webm only, so the tool stays focused on the one conversion it promises and rejects everything else with a clear message.
Decodes VP8, VP9 and AV1
The server handles the common WebM video codecs, including AV1 clips from newer browsers and screen recorders, then re-encodes them to H.264.
Audio converted to AAC
Opus or Vorbis audio from the first audio track becomes 128 kbps AAC inside the MP4, which phones, browsers and televisions all recognise.
Three quality presets
High keeps the most detail, balanced suits everyday sharing and small produces the lightest file, so you can trade size for quality without knowing bitrate settings.
Plays in every current player
The MP4 is written with faststart metadata, so web players and messaging apps can start playback before the whole file has downloaded.
Automatic deletion
The WebM upload and the converted MP4 exist only in a temporary folder and are removed automatically after your download finishes.
How to use WebM to MP4
- 01
Add the WebM file
Drop the .webm file into the workspace or click Choose file. Uploads up to 100 MB are accepted.
- 02
Pick the output quality
Balanced is the safe default. Choose high for detailed footage or small when the MP4 needs to be easy to share.
- 03
Convert to MP4
Click Convert to MP4 and follow the upload bar, then wait while the server re-encodes the video and audio.
- 04
Preview and download
Check the result in the built-in player, then download the MP4 with a filename based on the original clip.
Supported formats and limits
- Input
- WebM
- Output
- MP4
- Processing
- Server-side FFmpeg job in a temporary directory, deleted after download.
- Maximum size
- Up to 100 MB
- Requirements
- Chrome, Edge, Firefox or Safari · Server-side FFmpeg conversion
Limitations worth knowing
- Accepts .webm files only, up to 100 MB, one file per job.
- Video is re-encoded, so the MP4 is not a bit-for-bit copy and some detail is lost.
- Transparent WebM video becomes opaque, and HDR or Dolby Vision content is converted to standard SDR color.
- Jobs stop after three minutes, so long 4K WebM recordings may not finish.
Privacy and file handling
Your WebM file is uploaded to a temporary working directory on our server, re-encoded to MP4 with FFmpeg, and streamed back to your browser. The upload and the converted MP4 are deleted automatically when the download completes; nothing is stored permanently, analysed or shared.
Read the full privacy policy