Cut MKV

How to Cut MKV Files Online

1. Upload Your MKV File: Drag and drop or click "+ Add Files" to select Matroska clips from your device. Batch processing is supported, so you can queue several rips at once.
2. Set Start and Duration: In the Trim group, enter the start timestamp (HH:MM:SS or seconds) and either the duration or end time of the segment you want to keep. Multiple segments per file are supported when you re-add the source.
3. Adjust Codec and Quality (Optional): Leave the codec untouched to stream-copy without re-encoding (fastest, lossless). Otherwise pick a Video Codec (H.264, H.265, VP9, AV1), choose a Quality Preset, or set a CRF value (lower = higher quality). You can also constrain by Video Bitrate or pick a Resolution Preset (e.g. 1080p, 720p).
4. Cut and Download: Click "Cut". Files process in your browser session — no sign-up, no watermark, originals never leave the page.

Why Cut MKV Files?

Matroska (.mkv) is an open, royalty-free container based on EBML, announced on 6 December 2002 and now the de-facto wrapper for Blu-ray rips, anime releases, and home-server libraries. A single MKV can carry unlimited video, audio, subtitle, picture, and chapter tracks in one file — which makes it powerful, but also makes it the wrong shape for short shares, social posts, or quick previews. Cutting a clean segment out of a 12 GB rip is usually the first step toward almost anything else.

• Trim Blu-ray and DVD rips — Pull the actual feature out of a MakeMKV dump that includes trailers, FBI warnings, studio logos, and chapter previews. A 40 GB raw disc rip typically contains only ~2 hours of usable content.
• Share an anime moment without re-uploading the episode — Cut a 30-second scene from a fansub MKV with the ASS subtitle track intact; preserves typesetting, karaoke effects, and the original jpn audio.
• Make a YouTube-ready clip — Extract a single play from a sports broadcast or a single demo from a conference recording. YouTube accepts MKV but you'll often want to also cap length and drop unused audio tracks at the same time.
• Prep clips for Plex or Jellyfin testing — Slice a 90-second sample to reproduce a transcoding issue, then upload to a GitHub issue. Image-based subtitles like PGS force a full transcode in Jellyfin, and a tiny reproducer is far easier to debug than the whole movie.
• Pull intros, outros, or bumpers — Save the cold open of a TV episode or the credit sequence from a film for editing into a montage, keeping the source video stream intact.
• Cut training-data clips for ML or computer vision — Researchers often need 5-10 second action segments from longer surveillance, sports, or driving footage; MKV's chapter metadata makes finding the right window faster.

MKV vs MP4 vs WebM — Container Comparison

Property	MKV (Matroska)	MP4 (ISO BMFF)	WebM
First released	2002 (Matroska project)	2001 (MPEG-4 Part 14)	2010 (Google)
Standards body	matroska.org (open, royalty-free)	ISO/IEC 14496-14	WebM Project (subset of Matroska)
Allowed video codecs	Virtually any (H.264, H.265, AV1, VP9, ProRes, FFV1)	H.264, H.265, AV1 (plus more in practice)	VP8, VP9, AV1 only
Allowed audio codecs	Virtually any (AAC, AC-3, DTS, FLAC, Opus, TrueHD)	AAC, MP3, Opus (varies by player)	Vorbis, Opus only
Subtitle support	SRT, SSA/ASS, WebVTT, PGS, VobSub, USF	Limited (TX3G, WebVTT)	WebVTT only
Chapters	Yes, native	Yes, native	Yes, inherited from Matroska
Multiple audio/subtitle tracks	Unlimited	Yes, but tooling is weaker	Yes
HTML5 <video> playback	Not natively supported in any major browser	Universally supported	Chrome, Firefox, Edge, Opera; Safari since 14.1 (macOS 11.3+)
Typical use	Blu-ray rips, anime, archival masters	Phones, web, social, editing	Web video, ads, YouTube alt-source

Lossless Cut vs Re-encode — Which Mode Should You Pick?

Mode	What it does	Speed	Quality	Trade-off
Stream copy (no re-encode)	Demuxes and remuxes the existing video/audio packets	Very fast (10-100× real time)	Identical to source	Cut points snap to the nearest keyframe (often 1-10 seconds away from your target)
Smart cut	Re-encodes only the GOP at each cut edge, copies the rest	Medium	Near-lossless; one re-encoded keyframe per edge	Tooling support is limited; some codec combinations don't allow it
Full re-encode	Decodes and re-encodes every frame between your cut points	Slow	Frame-accurate, but a generation loss applies	Use when you need exact cuts or want to change codec/resolution at the same time

If you don't change the Codec or Quality settings, xconvert performs a stream copy — your trimmed clip will be byte-identical to the source between the actual keyframe boundaries. Pick a codec or CRF only if you also need to recompress or change container compatibility (for example, converting to MP4 for iPhone or social sharing).

Frequently Asked Questions

Why does my MKV cut not start exactly where I asked?

H.264, H.265, VP9, and AV1 all use inter-frame compression: most frames depend on a nearby keyframe (an I-frame) to be decoded. When you cut without re-encoding, the tool can only split at those keyframes. A 1080p Blu-ray rip typically has one keyframe every 1-10 seconds, so the actual start may snap to the nearest keyframe before your requested timestamp. If you need frame-accurate cuts, re-enable the Video Codec and Quality settings to force a re-encode at the edges.

Will all my audio tracks and subtitles be preserved?

Yes for a default stream copy — every embedded audio track (English DTS-HD, Japanese FLAC, director's commentary) and every subtitle track (SRT, SSA/ASS, PGS Blu-ray subs) is muxed into the output with the same language tags. If you re-encode, the audio is re-encoded with the selected Audio Codec and text-based subtitles are preserved; image-based PGS/VobSub subtitles pass through but may need a player that supports them.

Can I cut multiple segments from one MKV in a single pass?

Yes — re-add the same source file for each segment you want, set distinct start/duration values per copy, and queue them together. Each output is a separate trimmed MKV. To stitch the segments back into one file afterwards, use mkvmerge --append from MKVToolNix or the equivalent FFmpeg concat demuxer locally.

What's the difference between cutting MKV and cutting MP4?

The mechanics are identical at the codec level (both can stream-copy or re-encode), but MKV preserves features that MP4 can't carry cleanly: PGS subtitles, multiple lossless audio tracks like DTS-HD MA or TrueHD Atmos, and rich chapter metadata. If you cut an MKV then convert it to MP4, you may lose subtitle tracks the destination container doesn't support. If you only need MP4 from the start, cut MP4 directly.

Why won't my cut MKV play in Chrome or Safari?

No major browser natively supports the MKV container in the HTML5 <video> tag, even when the inside codecs are H.264/AAC that the browser can decode. To play in a browser, either install a player like VLC or convert the trimmed output to MP4 or WebM. Note that WebM is technically a subset of Matroska — same EBML structure, but restricted to VP8/VP9/AV1 video and Vorbis/Opus audio so browsers can guarantee playback.

Does cutting an MKV reduce quality?

Not when you use the default stream-copy mode — the underlying video packets are not re-encoded, so the output is mathematically identical to the source within the keyframe boundaries. Quality only changes if you select a Video Codec or set a CRF/bitrate, which triggers a full re-encode and produces one generation of compression loss.

Can I keep MKV chapters when cutting?

Yes, when stream-copying chapter markers within your selected segment are retained and timestamps are rebased to start at zero. Chapters that fall outside the cut window are dropped. If you re-encode and your output goes through a player that doesn't read MKV chapters, you can still view them in MKVToolNix, VLC, mpv, Plex, or Jellyfin.

Will the file size scale with the cut length?

For a stream copy, yes — almost linearly. Cutting a 60-minute, 8 GB H.265 MKV down to 6 minutes yields roughly an 800 MB file, because the per-second bitrate doesn't change. If the result is still too large for your destination (Discord's 10 MB free cap, Gmail's 25 MB attachment limit, or a 100 MB upload form), follow up with Compress MKV to lower the bitrate, or convert to a more efficient codec.

How is this different from MKVToolNix or LosslessCut?

Both are excellent desktop tools — MKVToolNix is the reference muxer for the format, and LosslessCut wraps FFmpeg with a friendly UI for keyframe-based trims. xconvert runs the same FFmpeg-grade pipeline in your browser session, so there's nothing to install and no upload-then-download round-trip on an ironman or M-series Mac; the trade-off is that very large rips (10+ GB) are faster in a native desktop tool that can use your full SSD bandwidth.