WebM to MKV
Converter
Convert WebM videos to MKV on your device. Free conversion for clips up to 50 MB, with no file uploads.
Choose WebM
Drop one file here, or choose it from your device.
One clip · 50 MB · up to 1080p input. Output fits 1280 × 720 at 30 fps. Audio is kept when present.
MP4, MOV, and MKV use H.264 and AAC. AVI uses MPEG-4 and MP3. WebM uses VP8 and Opus. HDR, multiple audio tracks, and subtitles are not supported.
The converter downloads about 32 MB on first use. Short clips work best; processing speed depends on your device. Keep this tab open.
How it works
- Choose a WebM file within the limits above.
- Convert to MKV. Cancel at any time; your original stays unchanged.
- Download the verified result before leaving or reloading this page.
These tools re-encode video. Quality may change, output can be larger, and source metadata is removed. Clips that exceed limits are rejected rather than trimmed. The whole output is decoded before its download appears.
Video converters
Your privacy
Your file is processed on this device, usually in a separate worker. We do not upload it. Cancel stops processing or discards its result; clearing or leaving this page releases the selection and results. Saved downloads remain on your device. With your permission, Google Analytics measures visits, conversion outcomes, download clicks, and errors and may use cookies; our events do not include file contents or filenames.