How to Convert WebM to MP4 (Screen Recordings, iPhone)

To convert WebM to MP4, re-encode the video as H.264 and the sound as AAC, so it opens in the apps and devices that refuse WebM. Our MOV to MP4 converter takes WebM files: choose the file, press Start, and download an MP4. Because WebM uses different video formats from MP4's usual one, the video is re-encoded, at high quality. It's a pro tool you can try with a free account on videos up to 30 seconds.

Where WebM files come from

WebM is an open video format made for the web. You'll typically get one from:

• Browser-based screen recorders and meeting tools, which record in the formats browsers handle natively.
• Recording a tab or a call with a browser extension.
• Downloading a clip from a website or a social platform.
• Animated stickers and short loops saved from websites.

Inside, a WebM usually holds VP8, VP9 or AV1 video with Opus or Vorbis sound. Browsers play them happily. The trouble starts when you leave the browser.

Why you'd want MP4 instead

• iPhone and iPad. The Photos app and iMovie don't accept WebM files, so you can't save the recording to your camera roll or edit it there.
• Editing apps. Many video editors, especially older versions, won't import WebM or import it without sound.
• PowerPoint and Keynote. Inserting an MP4 is far more reliable than a WebM.
• Sharing. Colleagues on older laptops, smart TVs and some messaging apps play MP4 without fuss.

MP4 with H.264 and AAC is the format they all agree on. For the general background, see what a video codec is.

Step by step

1. Open the MOV to MP4 converter and sign in.
2. Under Choose a file, pick your WebM, up to 1 GB and 30 minutes.
3. Press Start. The page checks the video's length in your browser first (see the note below if it can't).
4. Wait while it converts. Re-encoding takes a little longer than a simple repackage.
5. Press Download result to save your MP4. It's kept for 1 hour.

If you see "We couldn't read that file"

Before anything is uploaded, the page asks your browser how long the video is. Many WebM files made by browser-based recorders and meeting tools don't store their length, so the browser can't report it and the page stops with "We couldn't read that file." Nothing is uploaded and no free try is used.

If that happens, check whether your recorder can save as MP4 directly (many now can), or open the recording in a desktop video editor or media player that can export MP4. WebM files downloaded from websites usually do store their length and convert normally.

On an iPhone

Use Safari: press Choose a file, pick the WebM from Files (downloads usually land there), press Start, then Download result. Open the MP4 in Files, tap the share button and choose Save Video to put it in Photos.

What happens to quality

Since WebM's usual video formats can't simply be moved into an MP4 that plays everywhere, the converter re-encodes them (a rare WebM that already holds H.264 is just repackaged unchanged):

• Video becomes H.264 at a high-quality setting. Hard to tell from the original at normal viewing.
• Sound (Opus or Vorbis) becomes AAC at 160 kbps, the standard MP4 sound.
• Size: recordings larger than 1080p are scaled down to 1080p. Recordings at 1080p or below keep their size.

That last point matters for screen recordings. If you recorded a 1440p or 4K monitor, small text in the MP4 will be a little softer, because the picture is scaled to 1080p. For tutorials where viewers need to read code or menus, record at 1080p (or zoom your screen in) so nothing is scaled down.

The file size can go either way. VP9 and AV1 are efficient, so the MP4 may be somewhat bigger than the WebM; older VP8 recordings often come out smaller. If you need it smaller, use the video compressor instead, which also accepts WebM and gives you a compact MP4 in one step.

Only need the sound?

If the WebM is a recorded talk, a podcast clip or a song, you may not need video at all. Video to MP3 extracts the audio as an MP3 (a pro tool, free to try on videos up to 30 seconds). See how to convert WebM to MP3.

Tips for screen recordings

• Trim the start and end where you clicked "record" and "stop". Use trim video, which also accepts WebM and outputs MP4, so you can skip the separate conversion. See how to trim a video.
• Add captions for viewers watching without sound with the subtitle generator. See how to add subtitles to a video.
• Make a GIF of a short interaction for documentation or a chat; see how to make a GIF from a video.

For other formats, see how to convert MKV to MP4 and how to convert AVI to MP4.

Trying it free

MOV to MP4 is a pro tool. A free account can try it on videos up to 30 seconds, and you get 5 free tries a day across all our pro tools. That covers many quick screen recordings. Longer videos, up to 30 minutes and 1 GB, need a paid plan.

Your files and privacy

Conversion runs on our servers, so your video is uploaded. It's deleted as soon as it's converted, and your MP4 is available to download for 1 hour, then deleted too. If your screen recording shows private information, such as emails or account numbers, trim or blur it before sharing the result with anyone.

Convert your WebM

Choose your WebM in the MOV to MP4 converter, press Start and download an MP4 that opens in editors, PowerPoint and on iPhones. Clips up to 30 seconds can be tried with a free account.