Convert MKV to WEBM
Convert MKV files to WEBM in seconds. Free, no upload, no watermark. Trim, compress or edit before you convert.
or drag & drop videos, audio or images here, or paste with Ctrl+V
MP4 · MOV · MKV · AVI · WebM · WMV · FLV · GIF · MP3 · WAV · M4A · and 40+ more
- Files never leave your device
- No sign-up, no watermark
- Free forever
How to convert MKV to WEBM
- Add your MKV fileClick “Choose files” or drag & drop your MKV file onto the page.
- Check the outputWEBM is pre-selected. Optionally trim, crop, compress or tweak quality in the tabs.
- Convert & downloadClick “Convert & download”. Your WEBM file is created on your device and saved instantly.
MKV vs WEBM
Short answer: WebM is an open, royalty-free format designed for the web. It uses VP8 or VP9 video with Opus or Vorbis audio and is natively supported by Chrome, Firefox, Edge and modern Safari.
What is MKV?
MKV (Matroska) is a flexible open container that can hold almost any video, audio and subtitle tracks in one file. Popular for movies and archiving.
What is WEBM?
WebM is an open, royalty-free format designed for the web. It uses VP8 or VP9 video with Opus or Vorbis audio and is natively supported by Chrome, Firefox, Edge and modern Safari.
Quality
If the video and audio codecs inside your MKV file are already compatible with WEBM, we copy them without re-encoding: it's instant and lossless. Otherwise we re-encode with a high-quality setting (adjustable with the Quality slider).
| MKV | WEBM | |
|---|---|---|
| Full name | Matroska Video | WebM (Matroska-based) |
| Type | video | video |
| Best for | Movies, multiple audio/subtitle tracks and archiving | Websites, HTML5 video and open-source projects |
| MIME type | video/x-matroska | video/webm |
Last updated 2026-11-13
MKV to WEBM: FAQ
Is this MKV to WEBM converter free?
Yes. Converting MKV to WEBM is completely free with no watermark, no sign-up and no file limits beyond what your device can handle. Optional Pro features like 4K export and AI subtitles are available if you need them, and a single 4K export can be unlocked without a subscription.
Are my MKV files uploaded to a server?
No, never. The conversion runs entirely in your web browser using FFmpeg compiled to WebAssembly. Your MKV file never leaves your computer or phone, and we never store it, which makes it private and fast.
Will I lose quality converting MKV to WEBM?
If the video and audio codecs inside your MKV file are already compatible with WEBM, we copy them without re-encoding: it's instant and lossless. Otherwise we re-encode with a high-quality setting (adjustable with the Quality slider).
How do I convert MKV to WEBM on iPhone or Android?
Open this page in Safari or Chrome on your phone, tap “Choose files”, pick your MKV file and tap “Convert & download”. No app install needed.
Can I convert multiple MKV files to WEBM at once?
Yes. Select several files and click “Convert all”. You can download them one by one or as a ZIP. Free users can batch-convert up to 5 files at a time; Pro removes the limit.
Can I edit the MKV before converting?
Yes: trim, cut, crop, rotate, resize, change speed, adjust colour, add text, music or subtitles, and more, all before you export to WEBM.