How to Convert WebM to MP4 (Screen Recordings Too)

To convert WebM to MP4, open Convert to MP4, add the WebM file, choose a Quality, and press Convert to MP4. The VP8 or VP9 video is re-encoded as H.264 with AAC sound — the MP4 format that iPhones, PowerPoint, video editors and every social site accept. It runs in your browser, so the file isn't uploaded.

Convert WebM to MP4 step by step

1. Open Convert to MP4.
2. Add the WebM file — click, drop or paste it — or paste a direct link to one.
3. Choose the Quality:
   • High — visually identical to the original.
   • Standard — a good balance (the default).
   • Smaller file — for sharing and email.
4. Press Convert to MP4, wait for the progress bar, and download the MP4.

Where WebM files come from

• Screen recorders in browsers (Chrome, Firefox) and many extensions record WebM.
• Downloaded web videos — WebM is an open format made for websites.
• Messaging and meeting apps that record in the browser.

WebM plays fine in Chrome, Firefox and Edge, but not in some places that matter: older iPhones and Apple apps, PowerPoint on some systems, many TV players and several upload forms.

Screen recordings without a length

WebM files made in the browser often don't store their total length, so players show no duration and can't seek properly. The converter reads through the whole file, and the MP4 it produces has a proper length and seeks normally.

Tips for converting screen recordings

• Trim first with the Video Cutter — removing the start and end where you clicked Record and Stop keeps the conversion short.
• Choose Standard or Smaller file — screen recordings of slides and apps compress very well.
• Record MP4 directly next time: the Screen Recorder saves MP4 in browsers that support it (recent Chrome and Edge), so no conversion is needed.

How long does it take?

The video has to be re-encoded, so it takes roughly the length of the video for HD recordings on an ordinary laptop — less for small screen recordings, more for long 1080p or 4K clips.

Using the MP4 in PowerPoint and Keynote

1. Convert the WebM to MP4 as above.
2. In PowerPoint, choose Insert › Video › This Device (or Movie from File on a Mac) and pick the MP4. In Keynote, drag the MP4 onto a slide.
3. Set it to play automatically or on click in the video's playback options.

MP4 with H.264 is the format both apps handle most reliably, on Windows and Mac.

Uploading to social sites

Instagram, TikTok and Facebook accept MP4 far more reliably than WebM — some reject WebM outright, others accept it but convert it badly. Converting first gives you control over the quality. If the result is too large for the site, shrink it with Compress Video.

Other formats

Need MOV, MKV, AVI or FLV instead? The Video Format Converter uses the same engine with more outputs. Going the other way — MP4 to WebM for a website — is there too.

Privacy

Converting happens on your device with ffmpeg (WebAssembly); the first use downloads the video engine once. No upload, no watermark, no sign-up.

Frequently asked questions

Will the sound be kept?

Yes — Opus or Vorbis sound is converted to AAC, which MP4 players expect.

Is the quality reduced?

Re-encoding always changes the data a little, but at High the difference isn't visible. Screen recordings with text stay crisp.

Can I convert several WebMs at once?

One at a time; each conversion uses your device's full processing power.