WebM to MP4
Upload a WebM file and convert it to MP4 with H.264 video and AAC audio — the most universally supported combination across all devices, browsers, and platforms. This is the reverse of the MP4-to-WebM conversion and is useful when you have a WebM file that needs to play on older devices, Apple products, or platforms that don't support VP9.
The tool re-encodes the video at high quality (CRF 23) and the audio at 128 kbps AAC, producing a clean MP4 that plays everywhere. Processing time depends on the video length and resolution.
Everything runs in your browser using ffmpeg.wasm — your video is never uploaded to a server.
By The Paper Room Editorial Team — Video Tools
Frequently asked questions
Why convert WebM to MP4?▼
MP4 with H.264/AAC is the most universally compatible video format. While WebM works in most modern browsers, MP4 has broader support across older devices, Apple products, social media platforms, and video editing software.
Will the conversion lose quality?▼
There is a small quality loss from re-encoding between lossy codecs, but the tool uses CRF 23 which is a high-quality setting. For most content, the difference is imperceptible.
Does this upload my video to a server?▼
No. The conversion runs entirely in your browser using ffmpeg.wasm. Your video stays on your device.