WEBM to MKV Converter
Convert WEBM to MKV in your browser. Free, no signup. Conversion files are not uploaded to Format Convertly servers. Learn the formats, then convert when your workflow needs MKV.
Choose a file or drag and drop
Drop your WEBM file here or
Choose file · Drag & drop · Public file link
- Processed on your device
- No conversion file stored on our servers
- Maximum file size: 100 MB
Conversion runs in your browser. Files are not uploaded to Format Convertly servers.
Processed on your device
No conversion file stored on our servers
Conversion Settings
Customize the output to match your needs.
Convert Quality
92%Output
Output options for this format are applied automatically during browser conversion. Drop your file above to begin.
Advanced settings
Additional Options
Quality or bitrate forces a re-encode. Width/FPS apply only when creating GIF or animated WebP.
How to Convert WEBM to MKV
Add your WEBM
Drop a WEBM file into the browser panel. Nothing is sent to a remote queue.
Confirm settings
Review optional quality/size settings, then confirm MKV as the output.
Download MKV
Convert locally and download the MKV file when processing finishes.
Why Convert WEBM to MKV?
Private by design
WEBM → MKV runs in your browser. Files are not uploaded to a remote conversion queue.
Ready for the next step
Convert when a site, editor, or teammate expects MKV instead of WEBM.
Practical quality
MKV: codec-dependent. Lossy targets trade size for speed — preview when it matters.
Wide compatibility
WEBM is commonly used for HTML5 website video and Browser screencasts.
WEBM vs MKV
A quick side-by-side before you convert — deeper comparison lives on the full guide.
| Feature | WEBM | MKV |
|---|---|---|
| Kind | video container | video container |
| Compression | codec-dependent | codec-dependent |
| Lossy / lossless | Typically lossy | Typically lossy |
| Transparency | Not supported / N/A | Not supported / N/A |
| Best for | HTML5 website video; Browser screencasts | Multi-audio and multi-subtitle movies; Archival rips with chapters |
| Typical size | Competitive with H.264 MP4 at similar visual settings | Matches the encoded streams; often large for high-bitrate rips |
| Browser / web support | Good in modern Chrome, Firefox, Edge; test Safari targets | Poor compared with MP4 — convert for web |
| Compatibility | Strong in Chromium and Firefox; test Safari and convert to MP4 when editors or iOS-centric clients reject WebM | Excellent in VLC and enthusiast players; variable on iOS, some smart TVs, and web players that expect MP4 |
Choose WEBM when…
- HTML5 website video
- Browser screencasts
- Open-source distribution
- Short web app clips
Choose MKV when…
- Multi-audio and multi-subtitle movies
- Archival rips with chapters
- Open-source container workflows
- Flexible track layouts
What happens to video quality?
MKV compatibility: Excellent in VLC and enthusiast players; variable on iOS, some smart TVs, and web players that expect MP4
Tip
Converting from WEBM cannot restore detail already removed by lossy compression.
Does WEBM to MKV reduce quality?
MKV is typically lossy (codec-dependent). Use a higher bitrate when fidelity matters, and keep the WEBM master for archival.
MKV format guide →Should I keep the original WEBM?
Yes when you may need to re-encode later. WEBM: WebM is built for HTML5 video with open codecs — common for browser recordings and site backgrounds. Convert to MP4 when you need maximum device and editor compatibility, especially in Apple-heavy workflows.
WEBM format guide →WEBM · MKV
Related converters WEBM
Related converters MKV
Frequently Asked Questions
More on quality loss: conversion quality guides · problem-solution guides
Does converting WEBM to MKV reduce quality?
It can — both sides are typically lossy. A careful encode may look similar; repeated re-encodes cause generational loss. Prefer converting once from the best master you have.
Can you recover quality after converting?
Not from a lossy output alone. Return to the original master (or a better source). Converting to a lossless format does not resurrect discarded detail.
What is generational loss?
Damage that stacks when you decode and lossy-encode the same file over and over (for example JPG→edit→JPG). Edit from masters and export delivery formats once.
Where can I learn more about conversion quality?
Browse Format Convertly’s Quality guides for topics like whether conversion reduces quality, JPG↔PNG myths, WebP/MP3/MP4 tradeoffs, recovery limits, and generational loss — each links to the right converter.
What is a WEBM file?
WEBM is an open web media container typically carrying VP8/VP9/AV1 video and Opus audio. WebM is built for HTML5 video with open codecs — common for browser recordings and site backgrounds. Convert to MP4 when you need maximum device and editor compatibility, especially in Apple-heavy workflows.
Is WEBM lossy or lossless?
WEBM is typically lossy (codec-dependent). That keeps files small but means discarded detail cannot be restored later.
What is a MKV file?
MKV is a Matroska multimedia container that can hold many video, audio, and subtitle tracks. MKV is a flexible open container beloved for rips and multi-track films (commentary, subtitles, multiple audio languages). Convert to MP4 when a device or web platform refuses Matroska.
Is WEBM to MKV private?
Yes. The file is processed locally in your browser and is not uploaded to Format Convertly servers.
Ready to Convert Your Files?
WEBM to MKV privately in your browser.