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How to Convert WebM to MP4 on iPhone

Updated October 4, 2026 · 2 min read

WebM is the web's video format: browser screen recorders, website downloads and meme sites all produce it. On iPhone, though, a WebM won't save to Photos and won't open in iMovie or most editing apps. Converting it to MP4 fixes all of that.

What is WebM?

WebM is an open format created by Google for the web. It holds VP8, VP9 or AV1 video with Opus or Vorbis audio. iOS and almost every app expect MP4 with H.264 or HEVC instead. Because the codecs are different, WebM to MP4 is a real conversion — the video is encoded again, not just re-wrapped.

How to convert WebM to MP4 on iPhone

1. Save the WebM to Files. In Safari, long-press the link and choose Download Linked File. It goes to Files › Downloads.
2. Get the app. Download Video & Image Converter — free to try, no account.
3. Pick the WebM from the Files app.
4. Choose MP4. In More settings, pick H.264 if the video is going to an unknown device, or HEVC for a smaller file. The estimated size is shown before you start.
5. Convert and save. Save the MP4 to Photos and it behaves like any other video on your phone.

Is it safe to convert WebM without uploading it?

Yes. Online WebM converters need you to upload the file, then download the result — twice the data on a phone connection, with your video stored on a server you don't control. Video & Image Converter converts on the device itself. Nothing is uploaded and it works offline.

Can I convert MP4 to WebM?

Yes. WebM is one of the output formats too, with VP9 video — handy if you build websites and need a WebM version of a clip.