MP4 to WebM Converter

Convert MP4 videos to WebM for smaller file sizes and efficient web delivery. WebM (VP8/VP9) is ideal for HTML5 video. Processing runs locally in your browser.

Drop your file here, or

Files stay on your device

MP4 · MOV · WebM · MKV · AVI

No upload required100% free foreverWorks in your browser
How it works

MP4 to WebM Converter for private browser workflows

Smaller files for the web

WebM with VP9 encoding often produces smaller files than H.264 MP4 at similar quality, reducing bandwidth costs and improving page load times for embedded video.

HTML5 video ready

WebM is natively supported by all modern browsers. Use it as a primary or fallback source for HTML5 video elements alongside MP4.

Local browser conversion

The conversion runs on your device. Videos for client projects and internal use never leave your browser.

Common use cases

Create WebM versions of product demos and hero videos for faster page loads.

Website video

Reduce CDN and hosting costs by serving smaller WebM files to supported browsers.

Bandwidth savings

Use royalty-free WebM for open-source projects and platforms that prefer open codecs.

Open format publishing

Related tools

Video format conversion

WebM to MP4 Converter

Convert WebM videos to MP4 for playback on iPhone, Safari, editing software and platforms that do not support WebM. Processing runs locally in your browser.

Open tool
Browser-based video compression

Free Online Video Compressor

Reduce video file size for sharing, upload limits, presentations and websites. LessMB runs video compression in your browser so clips do not need to be sent to a remote server.

Open tool
Video format conversion

MP4 to MOV Converter

Convert MP4 videos to QuickTime MOV for Final Cut Pro, iMovie and Apple workflows. The conversion runs locally in your browser with no upload.

Open tool

Related guides

iPhone video compression

How to Compress a Video on iPhone

If an iPhone video is too large for email, chat, forms or shared drives, you can reduce its file size directly in Safari. LessMB runs video compression in the browser, so the clip stays on your device during the session.

Open guide
Email video compression

How to Compress a Video for Email

Email attachment limits are often much smaller than modern phone or screen-recording videos. LessMB can reduce video size locally and export a practical MP4 for sharing.

Open guide
Video storage FAQ

Does Google Drive Compress Video?

Google Drive stores your uploaded video file, but preview playback may use processed versions. If your goal is a smaller file for upload or sharing, compress the video before sending it to Drive.

Open guide
FAQ

MP4 to WebM Converter FAQ

Answers for the most common questions about this tool, supported workflows, and local browser processing.

No uploadFree toolBrowser-based
Is converting MP4 to WebM free?

Yes. LessMB converts MP4 to WebM for free in your browser without an account.

Is WebM better than MP4?

WebM often achieves smaller file sizes and is royalty-free, but MP4 has broader device support. Many sites serve both formats.

Do all browsers play WebM?

Yes, all modern browsers (Chrome, Firefox, Safari, Edge) support WebM playback natively.