MP4 vs WebM: Which Video Format Should You Use?
Compare MP4 and WebM for compatibility, quality, file size and web use, and learn when to choose each format for websites, sharing and editing.
Quick answer: choose MP4 (H.264 + AAC) when you want a video that plays everywhere, on every device, app and platform. Choose WebM mainly for publishing video on websites, ideally alongside an MP4 version. Quality and size depend on the codec inside the file, not on MP4 or WebM themselves.
MP4 and WebM are both common video formats, and both work in modern web browsers. But they come from different worlds and are not equally supported everywhere.
Containers and codecs: the key idea
MP4 and WebM are containers. A container is like a box that holds several streams: video, audio and sometimes subtitles. What really determines quality and file size is the codec used to compress each stream.
| MP4 | WebM | |
|---|---|---|
| Video codecs | H.264 (most common), H.265/HEVC, AV1 | VP8, VP9, AV1 |
| Audio codecs | AAC (most common), MP3, others | Opus, Vorbis |
| Origin | MPEG standard, based on Apple's QuickTime format | Created by Google for the open web, based on Matroska |
| Licensing | Some codecs (H.264, HEVC) involve patent licensing | Royalty-free codecs |
So "MP4 vs WebM" is really "H.264/HEVC/AV1 + AAC" versus "VP8/VP9/AV1 + Opus/Vorbis".
Compatibility
| Where | MP4 (H.264) | WebM |
|---|---|---|
| Windows, macOS, iPhone, Android | Plays natively everywhere | Good on computers and Android; historically weaker on Apple devices |
| Web browsers | All major browsers | Chrome, Edge, Firefox; recent Safari versions support many WebM files |
| Video editing software | Universal | Support varies; some editors don't import WebM |
| Social networks and messaging apps | Accepted everywhere | Often not accepted, or converted |
| Smart TVs and older devices | Very widely supported | Less predictable |
For sharing and compatibility, MP4 with H.264 remains the safest format in existence.
Quality and file size
At the same visual quality, newer codecs produce smaller files:
- H.264 is the reference: universal, fast to encode, but less efficient than newer codecs.
- VP9 and HEVC usually achieve similar quality at a noticeably lower bitrate than H.264.
- AV1 is more efficient still, but encoding is slower and older devices may not decode it.
This means a WebM file with VP9 can be smaller than an MP4 with H.264 at the same quality, but an MP4 with HEVC or AV1 can be just as efficient. The container is not what makes the difference.
Using video on a website
If you publish video on your own website, you can offer both formats and let each browser pick the one it supports:
<video controls width="640" preload="metadata">
<source src="clip.webm" type="video/webm">
<source src="clip.mp4" type="video/mp4">
</video>
Browsers use the first format they can play. If you can only provide one file, choose MP4 with H.264 for maximum reach.
Other tips for web video:
- Keep clips short and compress them for the web: most visitors watch on phones.
- Use
preload="metadata"so the full video is not downloaded before the visitor presses play. - For decorative, silent background loops, a short muted MP4 or WebM is far lighter than an animated GIF.
Which one should you choose?
| You want to… | Choose |
|---|---|
| Send a video to someone, or post it on social media | MP4 |
| Edit the video in most software | MP4 |
| Make sure it plays on any phone, computer or TV | MP4 (H.264) |
| Publish on your own website, with an open, royalty-free format | WebM, ideally with an MP4 fallback |
| A screen recording from your browser is in WebM and won't open | Convert to MP4 |
How to convert between MP4 and WebM
Use the Video Converter: choose your file, select MP4 or WebM, and download the result. When a video already uses H.264, conversion to MP4 only changes the container, which takes seconds and keeps the original quality. To make the file smaller at the same time, use Compress Video, which outputs MP4.
Frequently asked questions
Is WebM better quality than MP4? Not inherently. Quality depends on the codec and bitrate used, not on the container.
Why won't my WebM file play on my iPhone or in my editor? Support for WebM has historically been limited on Apple devices and in some editing programs. Converting to MP4 solves this.
Does converting WebM to MP4 lose quality? WebM usually contains VP8 or VP9, which must be re-encoded to H.264 for MP4. At high quality settings, the difference is usually hard to see.