Video Trimmer

Cut a clip out of any video by start and end time — fast, and lossless because the streams are copied rather than re-encoded. Runs entirely in your browser; your video is never uploaded. Free on LK Forge — no sign-up.

By LK Forge · Published 6 August 2026 ·

Drop your file here, or click to choose Processed privately in your browser — nothing is uploaded

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100% private. Your file is processed in your browser with ffmpeg (WebAssembly) and is never uploaded. Big or long files take longer and use more memory — for those, trim first.

How does trimming without re-encoding work?

The Video Trimmer cuts a section out of a video by start and end timecode without re-encoding it. It runs ffmpeg with -ss before the input and -c copy, which seeks into the file and copies the compressed video and audio packets straight to the output, so the trimmed clip is identical in quality to the source and keeps the same container and codec. The trade-off is keyframe accuracy: a stream copy can only begin on a keyframe, so the cut snaps back to the nearest keyframe at or before the time you typed. Phone recordings usually place a keyframe every one to two seconds, while desktop-encoded footage can go much longer between them. For a frame-exact edit, set the start a little early. Times accept HH:MM:SS, MM:SS or plain seconds. Everything runs locally through ffmpeg.wasm, so your video is never uploaded; the engine itself downloads once per session, on your first trim.

How to Use the Video Trimmer

Three steps, all in your browser.

  1. Load your video

    Drag any video onto the box or click to choose one. The trimmer keeps the original format and quality.

  2. Set start and end

    Enter a start time and, optionally, an end time as HH:MM:SS (for example 00:00:05 to 00:00:15). Leave the end blank to trim to the finish.

  3. Cut & download

    Click Trim. The clip is cut by copying the streams — fast and lossless — then you can preview and download it.

Why does my cut start a second or two before the time I typed?

Lossless trimming and frame-exact start times are mutually exclusive — here is the trade.

Because this trimmer copies streams instead of re-encoding, the first frame of your clip has to be one the decoder can build on its own. In H.264 that means a keyframe (an IDR frame); every other frame is stored only as a set of differences from its neighbours and is meaningless without one. So when you ask for 00:01:07, the tool seeks back to the last keyframe at or before that point and starts there.

How far back depends entirely on how the source was encoded. The keyframe interval — the GOP length — was a choice the original encoder made and cannot be changed after the fact.

SourceFrame rateTypical GOPKeyframe everyWorst-case early start
Phone camera (iPhone / Android)30 fps60 frames2.00 s2.00 s
Phone camera, 60 fps mode60 fps120 frames2.00 s2.00 s
Browser screen recorder30 fps60 frames2.00 s2.00 s
Broadcast / DVD rip (PAL)25 fps50 frames2.00 s2.00 s
Streaming download30 fps150 frames5.00 s5.00 s
Long-GOP web encode30 fps250 frames8.33 s8.33 s
MJPEG webcam / DV / ProResAny1 frameEvery frameFrame-exact

The end time is not affected. Trailing frames can be dropped at any boundary, so the cut ends where you asked, to the frame. Only the start snaps.

The upside of the same design is that nothing is re-encoded: the trimmed file has bit-for-bit the same picture and sound as the source, at the same bitrate and in the same container, and a 90-minute source exports quickly because no pixels are ever decoded. If the start must be exact, set it a second or two early and leave the lead-in — far less costly than a full re-encode. All-intra sources carry a keyframe on every frame, so on those the cut is already frame-exact. After trimming, convert the clip with MOV to MP4, MKV to MP4 or MP4 to GIF.

Frequently Asked Questions

How do I trim a video?
Load your video, type a start time and (optionally) an end time as HH:MM:SS, and click Trim. The tool cuts that section out in your browser and lets you preview and download the result. Nothing is uploaded.
Does trimming reduce quality?
No — trimming does not reduce quality. The trimmer copies the video and audio streams instead of re-encoding, so the cut clip has the exact same quality as the original and the export is very fast. It keeps the same file format as your input.
How accurate is the cut?
Because it copies streams for speed, the cut snaps to the nearest keyframe near your start time, so it may begin a fraction of a second before the exact moment you entered. For most clips this is not noticeable; for frame-exact cuts, trim a little wider. Start and end times are entered as HH:MM:SS, for example 00:00:05 to 00:00:15.
Is my video uploaded to a server?
No — your video never leaves your device. Trimming runs entirely in the browser tab with ffmpeg compiled to WebAssembly, so the file is never uploaded, logged or stored — safe for private footage. The video engine (about 10 MB) downloads the first time you convert in a session; after that, no further network requests are made.
What time format should I use?
Use HH:MM:SS or MM:SS — for example 90 seconds is 00:01:30 or 1:30. You can also enter plain seconds like 90. Leave the end time blank to keep everything from the start point to the end of the video.

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