MKV Compressor
Compress MKV container videos online for free. Our mkv compressor lets you choose output resolution (240p to 1080p), video bitrate (250 kbps to 8 Mbps), and codec (VP9/WebM or H.264/MP4) — with optional audio track removal and subtitle track stripping for maximum size reduction. All processing happens in your browser using the native MediaRecorder API. No signup required.
Upload an MKV file, choose resolution, bitrate, codec, and optional track stripping, then compress it entirely in your browser. Your video never leaves your device.
Drop your MKV file here
or click to browse
MKV files are supported (MP4, WebM, MOV, AVI also accepted)
Why Use Our MKV Compressor?
Instant MKV Compression in Your Browser
Compress MKV container videos directly in your browser using the native MediaRecorder API — no server upload, no cloud processing, no waiting. Your mkv compressor runs entirely on your device.
Secure MKV Compressor Online
Your MKV file never leaves your device when you compress it. 100% client-side processing means complete privacy — no cloud storage, no server logs, no data exposure of any kind.
MKV Compressor Online — No Installation
Compress MKV videos directly in your browser with zero software downloads, no plugins, and no account required. Our free mkv compressor works on any modern browser on any operating system.
Strip Audio and Subtitle Tracks
MKV containers often carry multiple audio streams and subtitle tracks that add significant file size. Our mkv compressor lets you remove audio and subtitle tracks in one click for maximum size reduction.
Common Use Cases for MKV Compressor
Media Server & Plex Library Optimization
MKV files from Blu-ray remuxes and 4K rips can exceed 40–80 GB each. Compress mkv files to 1080p at 4–8 Mbps to cut library storage by 60–80% while keeping excellent visual quality for Plex, Jellyfin, and Emby.
Cloud Storage & Backup Reduction
Compress MKV videos before uploading to Google Drive, Dropbox, or OneDrive to stay within storage quotas. Reducing a 10 GB MKV to 720p at 2 Mbps typically produces a file under 500 MB for a 90-minute video.
Email & File Transfer Sharing
Compress MKV files to under 25 MB for Gmail and Outlook attachment limits, or under 2 GB for WeTransfer free tier. Strip subtitle and extra audio tracks first for the fastest size reduction before re-encoding.
Discord & Slack Video Clips
Compress MKV clips to under 8 MB (Discord free) or 50 MB (Slack) for direct sharing in team channels. Reducing a short MKV clip to 480p at 500 kbps typically fits a 2-minute clip under 8 MB.
Mobile Device Compatibility
MKV is not natively supported on iOS and many Android apps. Compress and re-encode your mkv compressor output to MP4 (H.264) for universal playback on iPhones, iPads, and Android devices without additional apps.
Long-Term Video Archiving
Compress large MKV archives of home videos, lectures, and recordings to a smaller footprint for long-term storage. Stripping unused subtitle tracks and secondary audio streams alone can reduce MKV size by 5–15%.
Understanding MKV Compression
What is MKV Compression?
MKV (Matroska Video) is an open-standard container format that can hold an unlimited number of video, audio, subtitle, and chapter tracks in a single file. Unlike MP4 or AVI, MKV is a container — not a codec — which means the actual video data inside can be encoded with H.264, H.265, VP9, AV1, or virtually any other codec. Our mkv compressor works by re-encoding the video stream at a lower bitrate and optionally smaller resolution, while stripping unused audio and subtitle tracks that inflate the file size. All processing happens locally in your browser using the native MediaRecorder API — your MKV file is never uploaded to any server.
How Our MKV Compressor Works
- 1Upload your MKV file:Drag and drop your MKV file onto the drop zone or click to browse. The file is loaded into the browser's video decoder — no data is sent to any server and your video never leaves your device.
- 2Choose compression settings: Select output resolution (240p to 1080p), video bitrate (250 kbps to 8 Mbps), output codec (VP9/WebM or H.264/MP4), and whether to remove the audio track or strip subtitle tracks. Lower resolution and bitrate produce smaller output files.
- 3Download the compressed video: The mkv compressor re-encodes your video in real-time using Canvas + MediaRecorder and downloads the output automatically when complete. The results panel shows original size, compressed size, and reduction percentage.
What Gets Compressed and Stripped
- Video Re-encoding:The video stream is decoded frame-by-frame, scaled to the target resolution via an offscreen Canvas, and re-encoded at the specified bitrate using your browser's hardware-accelerated encoder.
- Audio Track Removal:Enabling "Remove audio track" strips all audio from the output — useful when only the visual content is needed and audio adds unnecessary file size.
- Subtitle Track Stripping: MKV files commonly embed SRT, ASS, and PGS subtitle streams. The browser MediaRecorder API does not re-encode subtitle tracks, so they are automatically excluded from the output.
- Output Format: The compressed output is saved as WebM (VP9) or MP4 (H.264) depending on your codec selection — both are universally supported formats with better compression than raw MKV remuxes.
Important Limitations
The mkv compressor uses the browser's native MediaRecorder API, which processes video in real-time — a 90-minute MKV takes approximately 90 minutes to compress. Keep the browser tab active during compression. MKV files that use codecs not supported by your browser (e.g., H.265/HEVC on some browsers) may not load correctly — in that case, try a different browser such as Chrome or Edge. For very large MKV files (over 10 GB), consider trimming the video first.
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Frequently Asked Questions About MKV Compressor
An MKV compressor is a tool that reduces the file size of an MKV (Matroska Video) file by re-encoding the video stream at a lower bitrate, smaller resolution, or with a more efficient codec, and optionally stripping unused audio and subtitle tracks. Our free mkv compressor online works entirely in your browser — your MKV file is never uploaded to any server.
Reducing bitrate and resolution does reduce video quality, but the impact depends on your settings. At 4 Mbps and 1080p, most MKV videos look excellent for home viewing. At 2 Mbps and 720p, quality is good for streaming and sharing. Going below 500 kbps will produce visible compression artifacts. The default settings (2 Mbps, original resolution) are a safe starting point.
Absolutely. Our mkv compressor processes everything locally in your browser using the Canvas and MediaRecorder APIs. Your MKV file is never uploaded to any server, never stored, and never leaves your device. All compression happens entirely on your machine with zero data transmission.
Yes — 100% free, forever. No signup, no account, no premium tier, no file size limits, and no ads interrupting your workflow. Just upload your MKV, choose your settings, compress, and download.
The mkv compressor uses the browser's MediaRecorder API, which processes video in real-time — it plays the video through a Canvas element and records the re-encoded output. A 90-minute MKV takes approximately 90 minutes to compress. This is a limitation of the browser-native approach, which avoids the need for ffmpeg.wasm or server-side processing.
Yes. Enable the "Strip subtitle tracks" option before compressing. MKV files commonly embed multiple subtitle streams (SRT, ASS, PGS) that can add hundreds of megabytes to the file size. The browser MediaRecorder API does not re-encode subtitle tracks, so they are automatically excluded from the compressed output regardless of this setting.
The mkv compressor outputs either WebM (VP9 codec) or MP4 (H.264 codec) depending on your codec selection. WebM/VP9 typically achieves 30–50% smaller files than H.264 at the same visual quality. MP4/H.264 is the most widely compatible format, supported by virtually all devices, players, and platforms including iOS.
MKV files that use H.265/HEVC encoding are not supported by all browsers. Try opening the file in Chrome or Edge, which have the broadest codec support. If the video still won't load, the MKV may use a codec (e.g., AV1, VC-1) that your browser cannot decode natively. In that case, use a desktop tool like HandBrake to first convert the video stream to H.264.
Typical MKV compression achieves 40–85% size reduction depending on the original encoding and your target settings. Blu-ray remux MKV files (often 30–80 GB) can be reduced to 2–8 GB at 1080p with 4–8 Mbps bitrate. Stripping unused audio and subtitle tracks alone can reduce file size by 5–20% without any re-encoding quality loss.