Trim a video
Choose an MP4 or MOV, set where it should start and end (type the seconds or use the frame you paused on) and download the shorter clip as a new MP4. The cut is exact to the frame, not rounded to the nearest keyframe, and the video never leaves your device.
Checking what your browser can do…
How it works
- •Choose or drop a video. The page reads its size, length and frame rate and shows a preview.
- •Play or scrub the preview, then press "Use the current frame" under Start and End, or type the times in seconds.
- •Press Trim video. The page decodes from the keyframe just before your start point, drops the frames before it, and re-encodes the frames you kept as H.264. The sound is copied without re-encoding.
- •Download the new MP4. The original file is not changed.
- •The file is read with mp4box.js and written with mp4-muxer, two open-source libraries served from this site (licences: /tools/vendor/NOTICE-media.txt). Decoding and encoding use your browser's own WebCodecs; nothing is sent anywhere.
What it does and what it cannot do
- •Reads MP4, MOV and M4V up to 1 GB with H.264 video (HEVC from phones only where your browser can decode it). WebM, MKV and AVI are not supported.
- •Needs a browser with WebCodecs and an H.264 encoder: recent Chrome or Edge on a computer, Safari 16.4 or later, or Firefox 130 or later. The page checks first and says so if yours cannot.
- •The picture is re-encoded at a bitrate close to the original's, so it is not bit-for-bit identical; most people cannot see a difference. A lossless trim would have to cut at keyframes (often one to two seconds apart), which this tool does not do.
- •Copied sound is cut on its own short steps of about 1/45 of a second, so the sound can start or end a few milliseconds off the picture; you will not hear it.
- •One piece per run: to cut out a middle section, trim twice and join the parts with another tool.
- •Date, location and other metadata are not copied. HDR video is not tone-mapped.
Questions
- Is my video uploaded?
- No. Your browser reads, cuts and saves the video itself. The page downloads two small code files that read and write MP4, and nothing else leaves or arrives.
- Is the cut exact?
- Yes, to the frame. Many quick trimmers cut at the nearest keyframe and you get a second or two extra. This page decodes from the keyframe before your start point and throws away the frames before it, so the first frame of the result is the one you chose.
- Does trimming lose quality?
- Slightly: the kept frames are re-encoded with your browser's H.264 encoder at about the original bitrate. The sound is copied as it is.
- How do I pick the exact frame?
- Pause the preview where you want to start and press "Use the current frame". You can then fine-tune the number in seconds, for example 12.35.
- Why does my phone video not open?
- Many phone videos use HEVC (H.265). If your browser cannot decode it, the page says so before doing any work. Safari, or Chrome and Edge on a computer with hardware video support, usually can.
- Can I trim WebM or MKV?
- Not here. This page reads MP4, MOV and M4V only.