Trim MKV

How to Trim an MKV File Online

1. Upload Your MKV File: Drag and drop or click "Add Files" to select MKV (Matroska) videos — Plex / Jellyfin library rips, anime fansub releases, MakeMKV Blu-ray dumps, OBS recordings saved as MKV, or HDR remuxes. Multi-track MKVs with multiple audio languages, embedded subtitles, and chapter markers are all accepted. Batch is supported — drop in a season's worth of episodes at once.
2. Set Start Time and Duration (VIDEO_TRIM): Enter a start time and a duration to keep. Both fields accept seconds (12.5) or HH:MM:SS.sss format (00:21:45.500) for millisecond precision. Add multiple trim segments to extract several clips from one MKV in a single pass — useful for pulling every fight scene out of an anime episode or every goal out of a match recording.
3. Pick Output Mode (Optional): Default is stream copy — no re-encoding, bit-identical to source, original H.264/H.265/AV1 video and AC3/DTS/FLAC/Opus audio tracks preserved. Switch to re-encode if you need a smaller file or frame-accurate cuts: choose VIDEO_CODEC (H.264, H.265/HEVC, AV1, VP9, MPEG-2, MPEG-4, DivX, Xvid) or AUDIO_CODEC (AAC, AC3, EAC3, DTS, FLAC, Opus, Vorbis, MP3). Use VIDEO_RESOLUTION to scale (2160p, 1440p, 1080p, 720p, 480p, percentage, or custom width/height) and VIDEO_COMPRESSION for a quality preset (Highest → Lowest), CRF slider (18 = visually lossless for H.264/H.265, 23 = default, 28 = smaller; CRF 30 default for AV1/VP9), constant bitrate, or target file-size percentage.
4. Trim and Download: Click Trim. Files process in your browser session — download individually or as a ZIP. No sign-up, no watermark, no length cap on the output. Multi-GB Blu-ray remuxes work fine.

Why Trim MKV Files?

MKV (Matroska) is the open-source container of choice for high-bitrate archival video — Plex and Jellyfin libraries, anime fansub releases, MakeMKV Blu-ray and UHD rips, HDR10/Dolby Vision remuxes, and any source where you want to preserve multiple audio languages, forced subtitles, and chapter markers in a single file. Because MKV is a container (not a codec), trimming with stream copy is essentially free — the underlying H.264/H.265/AV1 video and AC3/DTS/FLAC/Opus audio bytes are written into a new MKV without decoding, so the result is bit-identical to that section of the source. Common reasons to trim:

• Plex / Jellyfin library cleanup — Strip the 90-second studio idents, the 10-minute "previously on" recap before episode 1 of a season, or the post-credits stinger that breaks autoplay. Stream-copy preserves every audio track and subtitle stream so the trimmed file still works with Plex's per-user language and subtitle selection.
• Anime episode trimming — Cut OPs and EDs from a 24-minute episode (the "skip intro" 90-second window), pull a single 30-second fight scene from a season, or split a 24-episode batch where each episode shares the same 1:30 OP cut point. Multi-track audio (Japanese + English dub) and embedded ASS/SSA subtitles transfer through unchanged.
• MakeMKV Blu-ray rips — A typical 2-hour Blu-ray remux is 25-40 GB. Trim to a single scene (a fight, a song, a director's commentary segment) without re-encoding the whole thing — a 2-minute slice of a 35 GB UHD remux drops to ~600 MB while keeping HDR10 metadata intact.
• Multi-track recordings — OBS recordings saved as MKV often carry separate microphone, desktop audio, and game audio tracks. Trim without flattening — the trimmed MKV still has all three tracks for later mixing in DaVinci Resolve or Audacity.
• Sharing under email and chat caps — Gmail caps at 25 MB, Outlook at 20 MB, Discord at 10 MB free / 25 MB Nitro / 50 MB Boost, WhatsApp at 16 MB. A 30-second trim plus optional re-encode brings most clips inside these limits — though for chat sharing you'll usually want to also convert to MP4 since Discord and WhatsApp don't preview MKV inline.
• HDR / Dolby Vision preservation — Re-encoding HDR content risks losing the metadata that triggers HDR mode on your TV. Stream-copy trimming keeps HDR10, HDR10+, and Dolby Vision metadata exactly as the source had it.

For a different output container after trimming, see MKV to MP4 (browser-friendly), MKV to WebM, or Compress MKV for size-only reduction without trimming.

Stream Copy vs Re-encode — When to Use Which

Property	Stream copy (default)	Re-encode
Speed	Seconds for any size, even 35 GB UHD remuxes	Proportional to clip length and codec
Quality	Bit-identical to source	Slight loss unless CRF 18-20 (H.264/H.265)
Cut precision	Snaps to nearest keyframe (1-10s typical)	Frame-accurate
Output codec	Same as input (H.264, H.265, AV1, etc.)	Any: H.264, H.265, AV1, VP9, MPEG-2/4, DivX, Xvid
Audio tracks	All preserved (multi-language, commentary)	Re-encoded; multi-track may flatten unless explicit
Subtitle / chapter / HDR metadata	Preserved (PGS, SRT, ASS, HDR10, DV)	May need explicit re-mux
Output size	Proportional to duration kept	Variable by CRF / bitrate
Best for	Plex archive trims, Blu-ray remuxes, HDR	Frame-accurate cuts, codec change, smaller file

If the moment you want starts mid-GOP (between keyframes), stream-copy snaps to the nearest preceding keyframe — typically within 1-10 seconds for Blu-ray remuxes (which use 1-2 second GOP), 5-10 seconds for streaming-style sources. For frame-accurate cuts (the exact frame a goal lands, the precise word in a podcast), enable re-encode and pick CRF 18-20 to keep the loss imperceptible.

MKV Codec Quick Guide

Source codec	Trim style	Notes
H.264 / AVC (most rips, OBS)	Stream copy	Universally supported, fastest trim
H.265 / HEVC (4K Blu-ray, anime)	Stream copy	Preserves 50% size advantage; most Plex clients support
AV1 (modern re-encodes)	Stream copy	Newest, ~30% smaller than H.265, slower to encode if changing
MPEG-2 (DVD rips in MKV)	Stream copy or re-encode to H.264	Re-encode shrinks file 3-5×
AC3 / EAC3 (Dolby)	Audio stream copy	Multi-channel surround intact
DTS / DTS-HD MA	Audio stream copy	Lossless DTS-HD preserved exactly
FLAC (audiophile rips)	Audio stream copy	Lossless preserved bit-perfect
PGS subtitles (Blu-ray)	Stream copy	Image-based subs transfer as-is

Frequently Asked Questions

Will trimming an MKV preserve all audio tracks and subtitles?

Yes — in the default stream-copy mode, every video, audio, and subtitle stream from the source is written into the trimmed output. A Blu-ray remux with English DTS-HD MA, Japanese AC3, director's commentary, English forced PGS subs, and full English/Spanish PGS subs comes out the other end with all five tracks aligned to the new start time. Re-encode mode may flatten to a single audio track unless you explicitly preserve the others — stream copy is the safe default for multi-track preservation.

Will HDR10 / HDR10+ / Dolby Vision metadata survive the trim?

Yes in stream-copy mode. The HDR metadata is part of the H.265/AV1 elementary stream and the MKV container's color descriptors — neither is touched when stream-copying. Your trimmed clip plays back in HDR mode on the same TVs and Plex clients that handled the source. Re-encoding HDR is risky: most ffmpeg presets strip Dolby Vision RPU or remap colors to SDR unless you explicitly carry the metadata, so for HDR sources you almost always want stream copy.

What's the maximum MKV file size I can trim?

There's no fixed cap. Trimming runs in your browser, so the practical limit is your device's available memory and patience for the upload. 35 GB UHD remuxes from MakeMKV work — competitors like online-video-cutter.com cap at 4 GB on the free tier and 4 GB even on premium; XConvert does not. Stream-copy is fast enough that even a 50 GB Blu-ray remux finishes in well under a minute once loaded since no transcoding happens.

Why does the cut start a few seconds earlier than I asked?

Stream-copy can only cut on keyframes (I-frames). Blu-ray and UHD remuxes typically use 1-2 second GOPs (so the cut snaps within 1-2 seconds of your timestamp), while streaming-style sources can have keyframes every 5-10 seconds. The cutter snaps to the nearest preceding keyframe so the first frame of the output decodes correctly. If you need the exact frame, enable re-encode in step 3 — that decodes and re-encodes from your timestamp, frame-accurate.

Can I trim an entire anime season in one batch?

Yes. Drop in all 24 episodes and apply the same start/duration (e.g., start 00:01:30 to skip the OP, duration 00:21:00 to keep the episode body). Per-file overrides are also supported if one episode has a slightly different OP length. All 24 trimmed files come back as a ZIP. This is dramatically faster than running through Avidemux or MKVToolNix per file, especially when each episode is a 1-2 GB 1080p file.

Will Plex / Jellyfin still scan and play the trimmed MKV correctly?

Yes. Stream-copy keeps the same codec, container, and stream layout that Plex/Jellyfin expect. Direct play continues to work on Apple TV, Roku, Shield, and the Plex/Jellyfin web players exactly as it did with the source. Watch out for naming — Plex matches files by filename pattern (Show Name - S01E01.mkv), so name your trimmed output the same as the source if you want metadata to auto-match.

Can I trim a Dolby Vision remux without losing the DV layer?

Yes in stream-copy mode. Dolby Vision Profile 7 (dual-layer, common on UHD Blu-ray rips) and Profile 8 (single-layer, streaming) are both preserved when the trim is stream-copy because the RPU metadata travels with the HEVC stream. Re-encoding Dolby Vision requires specialized tooling (dovi_tool, custom ffmpeg builds) and is outside what most browser cutters can do — stream copy is the only safe option.

Should I trim first or convert to MP4 first?

Trim first, always. Stream-copy trimming is essentially free (seconds) and reduces the source from 30 GB down to whatever portion you actually want. Running MKV to MP4 on a 30 GB remux is a much slower transcode than running it on a 600 MB trimmed clip — easily 10-20× faster end-to-end. The same applies for Compress MKV — trim down to the segment you want, then compress only that segment.

What's the difference between trimming and cutting an MKV?

Same operation in practice. Some editors reserve "trimming" for shaving the start and end while keeping the middle, and "cutting" for extracting a middle portion or splitting at a point. XConvert handles all three patterns through the same start time + duration controls — for cut-style mid-clip extraction framing, see Video Cutter, which uses identical controls.