Convert MOV to MKV — Free Online Tool
Convert MOV files to MKV while preserving your video and audio streams using H.264 and AAC — retaining subtitles, chapter markers, and multiple audio tracks in Matroska's open, flexible container. Ideal for moving Apple QuickTime footage into a universally compatible format without sacrificing quality.
to
FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
Drop your MOV file here
or click to browse
Free — no uploads, no signups. Your files never leave your browser.
Settings
Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
MOV and MKV both support H.264 video and AAC audio, but because this tool re-encodes using libx264 and AAC rather than stream-copying, the video and audio are fully transcoded into the new container. The H.264 video is encoded at CRF 23 (a visually lossless-to-the-eye quality level) and audio is encoded at 128k AAC. Subtitles, chapter markers, and multiple audio tracks embedded in the MOV file are carried over into the MKV output, since Matroska natively supports all of these. One thing to be aware of: MOV supports alpha channel transparency (e.g., from ProRes 4444 or PNG-encoded video tracks), but MKV does not — any transparency in the source file will be lost and composited against a black background during conversion.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the open-source multimedia processing engine that handles all demuxing, decoding, encoding, and muxing for this MOV-to-MKV conversion. |
-i input.mov
|
Specifies the input file — a QuickTime MOV container, which may contain video encoded in H.264, ProRes, MJPEG, or other codecs alongside one or more audio tracks, subtitles, and chapter data. |
-c:v libx264
|
Encodes the video stream using libx264, producing H.264 output — the most universally compatible video codec for MKV playback across desktop players, smart TVs, and streaming platforms. |
-c:a aac
|
Encodes all audio tracks using FFmpeg's native AAC encoder, converting whatever audio codec was in the source MOV (such as PCM, ALAC, or MP3) into AAC, which is widely supported within MKV. |
-crf 23
|
Sets the Constant Rate Factor for libx264 to 23, the default quality level — this produces visually high-quality H.264 video with efficient compression, suitable for most archiving and distribution use cases from MOV source footage. |
-b:a 128k
|
Targets an audio bitrate of 128 kilobits per second for the AAC output — a standard quality level that balances file size and audio fidelity, appropriate for dialogue, music, and general-purpose video content from MOV sources. |
output.mkv
|
Specifies the output filename and, by its .mkv extension, instructs FFmpeg to wrap the encoded H.264 video and AAC audio into a Matroska container, preserving any subtitles, chapters, and multiple audio tracks from the source MOV. |
Common Use Cases
- Making Apple Final Cut Pro or iPhone-exported MOV footage compatible with Linux-based video players and editors like VLC or Kdenlive, which handle MKV natively
- Archiving MOV recordings from QuickTime screen capture or camera imports into MKV for long-term storage using an open, non-proprietary container standard
- Preparing multi-track MOV files — such as those with separate dialogue, music, and effects audio tracks — for distribution in MKV, which preserves all audio tracks with clear metadata
- Converting MOV files that contain embedded chapter markers (such as lecture recordings or documentary cuts) to MKV while keeping those chapters intact for media players like Kodi or Plex
- Getting MOV footage off an Apple ecosystem workflow and into an MKV format accepted by subtitle muxing tools like MKVToolNix for further post-processing
- Reducing file size of large MOV files exported from DaVinci Resolve or Final Cut Pro by re-encoding to H.264/AAC inside MKV with controlled quality settings
Frequently Asked Questions
Yes — MKV natively supports both subtitles and chapter markers, and FFmpeg maps these streams from the MOV container into the MKV output during conversion. MOV also supports chapters and subtitle tracks, so this conversion preserves them reliably. If your MOV contains multiple subtitle tracks or languages, you may want to verify the output in a player like VLC to confirm all tracks are present and correctly labeled.
No — MKV does not support video transparency, so any alpha channel in the source MOV file will be lost during this conversion. Codecs like ProRes 4444 or PNG video tracks in MOV can carry transparency, but H.264 inside MKV has no mechanism to store it. If transparency preservation is critical, you should keep the file in MOV or consider a format like WebM with VP9, which does support alpha.
Because this conversion re-encodes the video using libx264 at CRF 23, there is technically a generational quality loss compared to the source — especially if the MOV already contained H.264 or a higher-quality codec like ProRes. CRF 23 produces visually high-quality output that is indistinguishable from the source for most viewers, but for professional mastering workflows you may want to lower the CRF value (e.g., CRF 18) to reduce compression further. If both files use the same H.264 codec, stream-copying with '-c:v copy' would avoid any quality loss entirely.
To improve video quality, lower the CRF value — for example, replace '-crf 23' with '-crf 18' for noticeably sharper output at the cost of a larger file. To increase audio fidelity, raise the bitrate flag, such as changing '-b:a 128k' to '-b:a 192k' or '-b:a 320k'. You can also swap '-c:a aac' for '-c:a libopus' if you want better quality-per-bit audio, since Opus outperforms AAC at lower bitrates and is fully supported in MKV.
Yes — on Linux or macOS you can wrap the command in a shell loop: 'for f in *.mov; do ffmpeg -i "$f" -c:v libx264 -c:a aac -crf 23 -b:a 128k "${f%.mov}.mkv"; done'. On Windows PowerShell, use 'Get-ChildItem *.mov | ForEach-Object { ffmpeg -i $_.Name -c:v libx264 -c:a aac -crf 23 -b:a 128k ($_.BaseName + ".mkv") }'. Batch processing is especially useful for large MOV libraries exported from Final Cut Pro or camera imports.
The output file size depends heavily on what codec was used in the source MOV. If the original contained a high-bitrate format like ProRes or uncompressed video, the MKV will be significantly smaller because H.264 at CRF 23 is far more efficient. If the source was already H.264 at a similar quality level, the output may be nearly the same size or slightly larger due to re-encoding overhead. The MKV container itself adds negligible overhead compared to MOV.
Technical Notes
MOV and MKV overlap significantly in codec support — both handle H.264, H.265, VP9, AAC, and FLAC — which makes this conversion straightforward from a compatibility standpoint. However, this tool performs a full transcode rather than a stream copy, meaning libx264 re-encodes the video and AAC re-encodes the audio regardless of what codecs were in the source MOV. This ensures maximum MKV compatibility but introduces a compression generation. One notable structural difference is that MOV uses the '-movflags +faststart' optimization to front-load metadata for web streaming, while MKV achieves streaming readiness differently and does not require this flag. Metadata like title, creation date, and track names embedded in the MOV's atoms are generally preserved by FFmpeg when writing to MKV's EBML-based metadata structure, though some QuickTime-specific metadata fields may not have direct MKV equivalents and could be dropped. Multiple audio tracks are fully supported in both containers and will be preserved. If your MOV source uses Apple-proprietary codecs like ProRes or DNxHR that are not in MKV's standard codec list, FFmpeg will transcode them to H.264, which is the expected and correct behavior for this tool.