MP4 to WEBM Converter
Free Online MP4 to WEBM Converter
Convert MP4 video files to WebM format instantly in your browser — no software to install, no registration, and no watermarks. Uploaded files are automatically deleted from our servers after one hour.
About the formats
MP4 (H.264/AAC) is the most widely supported video format, compatible with virtually every device, browser, and media player. WebM (VP9/Opus) is an open, royalty-free format developed by Google, optimized for web streaming and HTML5 video playback. WebM files are often smaller than MP4 at comparable quality, making them ideal for websites where bandwidth matters.
Quality settings
The CRF (Constant Rate Factor) slider controls the trade-off between file size and visual quality. Lower values produce better quality but larger files. The default value of 30 provides a good balance for most use cases. For high-quality archival, try 20–25. For smaller web-optimized files, use 35–45.
Frequently asked questions
Will I lose quality converting MP4 to WebM?
Converting between lossy formats always involves some quality loss because the video is re-encoded. To minimize this, use a low CRF value (e.g. 20–25). For most purposes the difference is not noticeable.
Is WebM supported on iPhones and Safari?
Safari on macOS and iOS supports WebM playback since Safari 16.4 (2023). Older Safari versions do not support WebM. If broad compatibility is important, MP4 remains the safest choice.
What is the maximum file size?
You can upload video files up to 200 MB. For larger files, try trimming the video first with our video cutter.
Similar conversions: MP4 to MOV, MP4 to MKV, WebM to MP4.