WebM to MP4 converter
Turn WebM recordings into MP4s that play on iPhones and in editors.
or drop them here, or paste them
Nothing is uploaded.
About WebM to MP4
Screen recorders and web apps often save WebM, which iPhones, QuickTime and many video editors won't open. This converter re-encodes it as H.264 video with AAC sound in an MP4, the most widely supported combination.
Re-encoding happens on your device using its built-in video encoder, so a recording of your screen, with whatever was on it, stays private.
WebM video is VP8, VP9 or AV1, which can't simply be copied into an MP4 that every device plays, so the picture is re-encoded. Your device's hardware encoder does most of the work, and a short screen recording is ready in seconds. Longer videos take roughly as long as they play, or less on a fast computer.
The MP4 keeps the resolution and frame rate of the original. The result plays on iPhones, in QuickTime, in PowerPoint and in most video editors. If your browser can't encode H.264, the page tells you before you start, instead of failing halfway.
Questions and answers
WebM uses different codecs (VP8, VP9 or AV1) than most MP4 players expect, so the video has to be re-encoded rather than copied.
Yes, when your browser can encode H.264, which current Chrome, Edge and Safari can. The result shows that it's an MP4.
No fixed limit. Long recordings take a while; keep the page open on your phone until it finishes.