Loading page
About this tool
Cut a clip out of a video file in your browser by setting a start and end time, with a fast stream-copy or a re-encoded output.
Trim Video cuts a chosen section out of a video file entirely inside your browser, using FFmpeg compiled to WebAssembly, so the footage is never uploaded to a server. You set a start and end time and it builds the standard FFmpeg command — seeking with -ss and cutting a duration with -t — in either fast stream-copy mode (-c copy, no quality loss) or a precise H.264 re-encode. It is for anyone who needs one clip out of a long recording without installing an editor.
Open Trim Video on AltFTool — it loads instantly in your browser.
Upload or drag in the file you want to work with.
Adjust the settings and preview the result.
Download the finished file to your device.
The video is processed locally in the browser, which matters for private or unreleased footage.
Stream copy is near-instant and lossless; the re-encode gives a frame-exact cut at a CRF you choose.
Output size is estimated from the source average bitrate — file size in bits divided by duration.
Not in stream-copy mode: -c copy repackages the existing compressed frames without decoding them, so the picture is bit-for-bit identical to the source. The precise mode re-encodes with H.264 at your chosen CRF (default 23), which is visually near-transparent but not lossless.
Because a stream copy can only cut on a keyframe, and FFmpeg moves the cut back to the nearest preceding one. Most phone and camera recordings place a keyframe every 2 seconds, so that is the worst-case drift. Switch to the precise re-encode mode for an exact start.
Roughly the source size multiplied by the fraction you keep: cutting 15 seconds out of a 60-second, 100 MB video gives about 25 MB. That holds for a stream copy because the average bitrate stays the same; a re-encode at a higher CRF will usually come out smaller.
No. The file stays in your browser's memory and is processed by FFmpeg running as WebAssembly. The only network request is a one-time download of the FFmpeg engine itself the first time you trim.