MP4 vs WebM: which should you use?
WebM is the web's open video format; MP4 is the one every device plays. We encoded the same 1080p clip for both at matched quality to compare size and speed.
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Quick answer: At the same quality a WebM is somewhat smaller than an H.264 MP4: on our 1080p test, VP9 WebM was about 15% smaller at good quality (VMAF 92) and about 6% smaller at very high quality, and took more than twice as long to encode. MP4 plays on every phone, computer, TV and editor; WebM plays in Chrome, Firefox and Edge but not everywhere else. Use WebM for websites and screen recordings that stay in a browser, MP4 for everything else.
Updated
Choose MP4 when
- You send, upload or edit the video.
- It has to play on an iPhone, a TV, a console or in WhatsApp.
- You want one file that works everywhere.
Choose WebM when
- The video lives on a website and you want smaller files.
- A browser screen recorder made it and it stays in the browser.
- You record PS5 clips for the web and want them smaller (PS5 offers both).
Same 1080p clip, matched quality
| Quality (VMAF) | MP4 (H.264) | WebM (VP9) | WebM is smaller by |
|---|---|---|---|
| Very high (about 95) | about 5.4 MB | 5.05 MB | about 6% |
| Good (about 92) | 3.50 MB | about 3.0 MB | about 15% |
| Time to encode | 20 s | 43–49 s | more than 2 times slower |
A 20-second 1080p cut of the Sintel trailer, made with the standard free software for each format at its usual speed setting, on a 4-core cloud PC, picture quality scored with VMAF (0–100) against the original frames, 20 October 2026. Sizes marked "about" are estimated between two encodes either side of that quality. Sintel © Blender Foundation, CC BY 3.0.
How it works
- Drop your videoThe file is read on your computer, never uploaded.
- ConvertMany videos convert in seconds with no quality loss; the rest are converted at high quality.
- Download the MP4Plays on Windows, Android, iPhone, Mac and every website.
What is inside each
A WebM holds VP8, VP9 or AV1 video with Opus or Vorbis sound, all open formats made for the web. An MP4 usually holds H.264 or HEVC video with AAC sound. The codec, not the file type, decides the size: an AV1 WebM can be far smaller than our VP9 one, and plays in even fewer places.
Where WebM plays
Chrome, Firefox and Edge play WebM, and so does Android. Many TVs, consoles, editors and messaging apps do not, and support on Apple devices is patchy. That is the usual reason to turn a WebM into an MP4: the converter above re-encodes the video to H.264 and the sound to AAC, in your browser, so the file plays everywhere.
Measured, not promised
From our tests on a 2019 Intel MacBook, an Apple M1 and a Windows PC without a graphics card. See all results.
Why your video never leaves your computer
Online video tools upload your file to their servers, process it there, and send it back. That is slow for big videos and costs them money for every minute, so free plans cap your file size or add watermarks, and your video sits on someone else's computer.
Here your own computer does the work, inside this tab. Nothing is uploaded, so there is nothing to cap: no file size limit, no daily limit and no watermark.
Questions
Is WebM better quality than MP4?
Not by itself. At the same quality, our VP9 WebM was 6–15% smaller than an H.264 MP4. Size and quality depend on the codec and settings.
Why is my converted MP4 bigger than the WebM?
H.264 needs more data than VP9 for the same picture, so the MP4 is usually a little bigger. That is the cost of playing everywhere.
MP4 or WebM for PS5 captures?
WebM makes smaller clips; MP4 opens in more editors and apps. Pick MP4 if you plan to edit or send the clips.
Can I convert several files at once?
Yes. Choose or drop several files together. They are converted one after another with the same settings, and you can download each one or all of them in one ZIP.
Is it really free?
Yes. Your computer does the work, so a video costs us nothing to process. No account, no watermark, no limits.
Is my video uploaded?
No. It is processed inside this browser tab and saved straight back to your computer.
Which browsers work?
Recent Chrome, Edge and Safari on a computer. Chrome and Edge are fastest on most machines. Phones work for short videos.
How long does it take?
In Chrome, a one-minute 1080p video took 13–19 seconds on the laptops we tested and about 40 seconds on a computer without a graphics chip. Safari can be slower.
Can I close the tab while it works?
Keep the tab open and in front until it finishes. Browsers slow down background tabs.