How to trim a video
- Choose your video. The whole of it is selected to begin with.
- Drag the start and end handles on the timeline under the preview, or type the times into the Start and End boxes. Both 1:30 and 90 mean ninety seconds in.
- Press Play the selection to watch just the part you are keeping. To set a point while watching, pause the video and press Start here or End here.
- Choose Fast cut or Exact cut, and whether to keep the sound.
- Press Trim video and save the result. Your original is never changed.
Fast cut or exact cut, and what keyframes are
Videos do not store every frame as a full picture. Every so often there is a keyframe, a complete image; the frames in between store only what changed since the one before. That is how a phone fits minutes of video into a reasonable file. It also means playback can only begin cleanly from a keyframe.
| Fast cut | Exact cut | |
|---|---|---|
| How | Copies the video, no re-encoding | Re-encodes the part you keep |
| Speed | Seconds | Roughly the length of the part you keep, longer on a phone |
| Start point | Nearest keyframe at or before your start, which can be a few seconds earlier | The exact frame you chose |
| Quality and format | Original quality, original format (MOV stays MOV) | MP4 with H.264, at a high quality setting |
For most purposes, such as cutting the fumbling at the start of a phone video or the dead time at the end, the fast cut is ideal. Choose the exact cut when a clip has to begin on a particular word or beat, or when you also want the result as an MP4 that plays everywhere.
When the preview does not play
Browsers play MP4 and most MOV files, but not every format. MKV and AVI files, and iPhone HEVC videos on some Windows PCs, may show no preview. The engine reads the video's length anyway, so the timeline still works: type your times and cut as normal. If you want to watch the result on that computer, choose Exact cut to get an MP4 that plays, or convert it with the video converter.
After trimming
- Too big to send on WhatsApp or by email? The video compressor fits it under 16 MB, 25 MB or any size you choose. Trimming first always gives a sharper result.
- Want a few seconds as a looping animation? Make it with video to GIF.
- Need to cut out a part from the middle, join clips, crop for Reels or add text? Use the video editor.
- Need it silent? Switch off "Keep the sound" here, or use the mute video tool on the whole video.
Location and other details stored by your phone are not copied into the trimmed file. The rotation is kept, so portrait videos stay upright.
The engine behind this tool
Video and sound are processed by FFmpeg, the open-source engine behind most of the world's video software, compiled to run inside your browser as ffmpeg.wasm. It is downloaded from this site (about 31 MB) the first time you use a video or audio tool, and your browser keeps it for next time. FFmpeg and ffmpeg.wasm are free software, licensed under the GNU General Public License version 2 or later; their source code is at github.com/ffmpegwasm/ffmpeg.wasm.