Video to MKV Converter

How to Convert Video to MKV Online

1. Upload Your Video File: Drag and drop or click "+ Add Files" to select MP4, MOV, AVI, WebM, FLV, MTS, M2TS, WMV, TS, MPEG, 3GP, VOB, or any of 30+ video formats. Batch upload is supported.
2. Pick Quality Preset or File Compression: Default is "Very High (Recommended)" which keeps near-source quality. Pick "Highest" for archival masters, "Medium" or "Low" to shrink large files, or switch to File Compression to target a Specific file size, Constant Bitrate, Variable Bitrate, Constant Quality (CRF), or Constraint Quality.
3. Resize, Trim, or Keep Original (Optional): Under Video resolution, pick a Preset Resolution (4K, 1440p, 1080p, 720p, 480p), enter a custom Width x Height, scale by Resolution Percentage, or leave Keep original. Use Trim to set a Time Range, or leave Unchanged to keep the full duration.
4. Convert and Download: Click Convert. Files process server-side and download as standard .mkv — no sign-up, no watermark, no email gate.

Why Convert Video to MKV?

MKV (Matroska) is an open, royalty-free container format announced in December 2002 by Steve Lhomme as a fork of the Multimedia Container Format. Version 1.0 shipped in 2004. The name comes from matryoshka — the Russian nesting dolls — because MKV nests an unlimited number of video, audio, subtitle, and chapter tracks inside a single file. Unlike MP4, MKV is not patent-encumbered and supports error recovery, fast seeking, and lossless codecs in the same container.

• Archive masters with lossless audio — MKV holds FLAC, PCM, and WavPack natively, so you can pair an H.264 or H.265 video track with a lossless audio codec (FLAC or PCM) for archival rips.
• Bundle multiple audio tracks and subtitles — A single MKV can carry English + Spanish + Japanese audio plus SRT/ASS/PGS subtitle tracks, switchable in VLC, MPC-HC, Kodi, Plex, Jellyfin, and Emby without external sidecar files.
• Plex and Jellyfin libraries — Most home media servers treat MKV as the default container because it preserves the source's audio commentary, forced subtitles, and chapter markers from a Blu-ray rip.
• HEVC / AV1 delivery without MP4 patent licensing — MKV legally wraps H.265, AV1, VP9, and Opus without the container-level licensing concerns that have historically complicated MP4 distribution.
• Camera and screen-recorder rescue — Recording apps (OBS Studio defaults to MKV, ShadowPlay, ffmpeg pipelines) write MKV first because it survives a crash mid-recording where an MP4 with an unwritten moov atom would not open.
• Cross-platform desktop playback — Native MKV playback works in VLC, MPC-HC, Kodi, mpv, IINA, and PotPlayer on Windows, macOS, and Linux. Chrome, Safari, and Firefox do not play MKV natively in the browser; convert to MP4 or WebM for web delivery.

MKV vs MP4 — Container Comparison

Quality Preset and Compression Mode Guide

Frequently Asked Questions

Why convert MP4 to MKV instead of keeping it as MP4?

Three reasons: you want to embed multiple audio tracks or subtitle tracks inside one file, you want lossless audio (FLAC/PCM) paired with the video, or you want the crash-resilient container for re-encoding pipelines and screen recording. For pure playback on phones, web browsers, or social media uploads, stay on MP4 — MKV gives you no quality benefit there and loses native browser playback. See MP4 to MKV and MKV to MP4 for the reverse.

Will my converted MKV play in Chrome, Safari, or Firefox?

No. None of the major browsers play MKV natively in the <video> tag — Chrome and Edge can sometimes decode the underlying video codec (H.264) but the Matroska container isn't on the supported list. For browser playback, convert to MP4 or WebM instead. On the desktop, VLC, MPC-HC, mpv, Kodi, and IINA all play MKV out of the box.

Which video codec should I pick inside the MKV?

xconvert defaults to a sensible codec per source. If you can override: choose H.264 for the broadest device compatibility, H.265 (HEVC) for ~30-50% smaller files at equivalent quality (Apple silicon and most 2017+ GPUs decode it in hardware), AV1 for the smallest files but the slowest encode, or VP9 as a royalty-free middle ground. MKV happily wraps all of them.

Does converting to MKV reduce or increase the file size?

MKV is a container — file size depends on the codec, bitrate, and resolution you choose, not on MKV itself. Re-encoding with the same codec and Quality Preset produces an MKV roughly the same size as the source. To shrink the file, switch to File Compression mode and pick a Specific file size, lower CRF target, or Medium/Low Quality Preset. Or use compress MKV after converting.

Can I keep my original subtitle and audio tracks during conversion?

If your source already contains multiple audio tracks or embedded subtitles (common in M2TS Blu-ray rips, MKV re-muxes, or some MP4 files), the converter carries them into the MKV by default. The audio is re-encoded to your selected audio codec rather than copied, and subtitle tracks (SRT, ASS, PGS) carry over in the MKV container.

Why does OBS Studio record to MKV instead of MP4?

OBS defaults to MKV because if the recording crashes or the power cuts, an MKV file is still playable — MKV writes metadata incrementally. An MP4's moov atom is written at the end of the recording, so a crashed MP4 is often unrecoverable. OBS exposes a "Remux to MP4" option after recording so you can keep the safety of MKV during capture and the compatibility of MP4 afterward. Our MKV to MP4 page handles that conversion.

What's the maximum file size or video length I can convert?

Free uploads are limited to 400 MB per file and 5 jobs at a time; Basic raises the video cap to 1 GB and Pro to 4 GB. Full-length movie rips and multi-hour screen recordings therefore need trimming first; server-side conversion itself is fast.

Can I batch-convert a folder of mixed-format videos to MKV?

Yes. Drop MP4, MOV, AVI, WebM, FLV, MTS, M2TS, WMV, TS, MPEG, 3GP, VOB, and other formats into the upload area at once. Each file converts independently with the same Quality Preset / resolution / trim settings. Use the format-specific pages — MOV to MKV, AVI to MKV, WebM to MKV — if you only have one source format and want preset defaults tuned for it.

Does MKV support 4K, HDR, and high-frame-rate video?

Yes. MKV has no resolution, bit-depth, or frame-rate ceiling — the limit is whatever the chosen video codec supports. H.265 and AV1 inside MKV handle 4K and 8K HDR at 60 fps and beyond. Set Preset Resolutions to 2160p (4K) or 4320p (8K) to keep the source resolution, or pick a lower preset to downscale.