WebM vs MP4: Which Screen Recording Format Should You Use?
WebM and MP4 both hold your screen recordings, but they behave differently. Here is a plain-English comparison so you can pick the right format for sharing, editing, or uploading.
You finished a recording, and now your tool is asking what format to save it as — or it handed you a .webm file and you’re wondering whether you need an .mp4 instead. It’s a small decision that quietly affects file size, quality, and whether the video plays where you’re sending it.
Here’s the plain-English version.
What a video format actually is
A file like .webm or .mp4 is a container — a wrapper holding your video stream, audio stream, and metadata together. Inside, the actual video is compressed by a codec. The container and codec together decide how small the file is, how good it looks, and where it plays.
You don’t need to memorize codecs. You mostly need to know: where is this video going?
WebM in one paragraph
WebM is an open, royalty-free format built for the web. It’s what browsers produce natively when you record a screen, and it typically gives you excellent quality at a small file size. It plays perfectly in every modern browser and on every major platform’s upload flow (YouTube, Slack, Google Drive, social).
MP4 in one paragraph
MP4 is the long-established, near-universal format. Its strength is compatibility: it plays in virtually every video player, editor, and device ever made, including older software that predates WebM. If something refuses to open your video, MP4 is the safe fallback.
Quick comparison
| WebM | MP4 | |
|---|---|---|
| Best for | Web, browsers, quick sharing | Maximum compatibility, older software |
| File size | Usually smaller | Slightly larger at similar quality |
| Browser playback | Native everywhere modern | Native everywhere |
| Video editors | Most modern ones | Every one |
| Licensing | Open, royalty-free | Patent-licensed |
So which should you pick?
For most people, most of the time, WebM is the right default. If you’re sharing a recording in Slack, uploading to YouTube, embedding on a site, or sending a link to a teammate, WebM is smaller and plays flawlessly.
Reach for MP4 when:
- You’re importing into an older video editor that chokes on WebM.
- You’re sending to someone on legacy software or an old device.
- A platform explicitly requires MP4 on upload.
If you land on a WebM file and need MP4, any free converter — or your video editor’s export dialog — will turn it into one in a click.
What this means for screen recording
Because screen recorders like ScreenKit run in the browser, they capture to WebM natively — which is exactly why your recordings come out small and web-ready without any extra processing. For the vast majority of use cases (demos, tutorials, async updates, bug reports), that’s precisely the format you want, and you can share it immediately.
Still images are a different question — for those you’ll want PNG, JPEG, or PDF, which we cover in our full-page screenshot guide.
The bottom line
Don’t overthink it. Record to WebM, share it as-is, and only convert to MP4 on the rare occasion something old-school demands it. You’ll get smaller files and cleaner playback almost everywhere.
Record web-ready video in one click. Add ScreenKit to Chrome — free, local, and WebM by default.