Video Trimmer — Cut Video Online
Drag the in/out handles to pick the part you want, then cut it loose. Trimming only the end of an H.264 clip copies the file as-is; anything else re-encodes on your device's own hardware, and the tool says which before you run it. Either way nothing leaves your browser.
Why one edge can be instant and the other can't
A video file stores most frames as a difference from the frame before it, not as a complete picture. Playing from any point past the very start means decoding forward through everything that comes before — there is no shortcut into the middle of a compressed stream.
Trimming only the end sidesteps this entirely: the start of the file is untouched, so the container can be rewritten to stop early without ever decoding a frame. That is a stream copy, and it is why it finishes almost instantly. Moving the start has no such shortcut, so the tool decodes and re-encodes the whole selection — on this browser's own hardware encoder rather than a slower WebAssembly one.
There is a second condition on that copy, and it is about the format rather than the cut: frames can only be moved across untouched if the browser can write the codec they are already in. H.264 and VP9 it can; HEVC — what most phones record — it can play but not write, so an HEVC clip is re-encoded even when only its end moves. The tool checks both conditions and says which path it is on before you start.
Frequently asked questions
Is trimming instant, or does it re-encode?
It depends, and the tool tells you which one is about to happen before you run it. Two things have to line up for an instant, packet-for-packet copy: the in-point has to still be at the very start, and the video has to already be in a format this browser can write back out — H.264, or VP9 where H.264 encoding is missing. A typical H.264 MP4 trimmed only at the end qualifies, and finishes in well under a second. Move the in-point at all, or bring an HEVC clip off a phone, and every frame is decoded and re-encoded instead.
Why can't cutting the start be instant too?
Because of how video compression works. Most frames in a video only store the difference from the frame before them, so starting playback partway through means decoding forward from the last full frame anyway. A cut that only trims the end never has this problem — the start of the file is untouched, so it can be copied as-is, provided the format is one this browser can write back out.
Is my video uploaded anywhere?
No. Both paths run entirely in your browser — the stream copy uses Mediabunny to repack the container, and the re-encode uses WebCodecs, a built-in browser API. Nothing is sent to a server, and there is no ffmpeg engine to download either way.
Which formats and browsers work?
MP4, MOV, MKV and WebM go in, up to 2 GB. Output is MP4 (H.264), or WebM (VP9) on browsers without an H.264 encoder — a trim writes one of those two whichever path it took. AVI, WMV, FLV and MPG are the exception: the browser's built-in video engine has no reader for them, so convert one to MP4 first and trim that. It needs a browser with WebCodecs: current Chrome, Edge, Safari and Firefox all qualify.
Does re-encoding lose quality?
A little, the way any re-encode does — this browser's own hardware encoder is used at a high quality setting, so the loss is small and usually not visible. Trimming only the end of a clip that is already H.264 avoids a re-encode entirely, and the tool says which path it is taking before you run it.
Is there a minimum or maximum length?
The selection has to be at least a fifth of a second — shorter than that is not really a clip. There is no fixed maximum, but selections past about fifteen minutes take a while when the run re-encodes, and the tool warns you before you start. A stream-copy trim has no such cost and raises no warning.
Can I trim the audio separately from the video?
No — the in/out range applies to the whole clip, audio included. If you need the audio on its own, extract it first and trim that file, or mute the video afterwards.