WebM to MP4
h.264 with AAC audio, which plays on effectively everything.
Your file
Drop a file here, or click to choose
It stays on this device. Nothing is sent anywhere.
Settings
Why convert away from WebM
WebM is a web format. Plenty of things that are not browsers refuse it: TVs, older phones, most video editors, PowerPoint, and a fair few social platforms. MP4 with h.264 is the closest thing to a universal video file.
Both WebM codecs are handled, VP8 and VP9, so it does not matter which one your file uses. This direction is also the fast one, since x264 encodes considerably quicker than libvpx in a browser.
Where your WebM probably came from
- A browser screen recorder. Anything using the MediaRecorder API produces WebM, which covers most in-browser capture tools, several meeting platforms and every "record your screen from a tab" extension.
- A saved video from a website. Sites serving WebM to browsers that support it will hand you a WebM when you save.
- A webcam or microphone capture made by a web application.
- Open source software exporting on principle, particularly on Linux.
In every one of those cases the file plays perfectly in the browser it came from and then refuses to open in the editor, uploader or presentation tool you wanted it for, which is a specific and very common kind of annoying.
What happens to the audio
A WebM carries Opus or Vorbis audio, and MP4 in this build carries AAC, so the sound is re-encoded rather than copied. That is a second lossy generation, and on speech at any reasonable bitrate it is inaudible. If the recording is music you intend to work on further, extract the audio separately with extract audio before converting, so you have an untouched copy to go back to.
Quality, and when to move it
The default of 23 is the h.264 standard and is the right answer for almost everything here, particularly screen recordings, which compress extremely well because most of the frame is unchanged between frames. Drop to 18 if the clip is going into an editor and will be encoded again afterwards, since each generation builds on the last. There is rarely a reason to go above 23 in this direction: you converted because you needed the file to work, not because you needed it smaller, and compress video is the tool for the latter.
Common questions
Will the quality drop?
A little, since it is a re-encode. At the default quality of 23 the difference is not visible in normal viewing. Lower the number to 20 if you want to be careful.
My screen recording came out as WebM. Is that normal?
Yes, browser-based recorders almost always produce WebM. Converting to MP4 is the usual next step before editing or uploading.