Is trimming a video lossless?

Only when the tool copies the original encoded packets without re-encoding. Many browser tools re-encode the selected section. The original stays safe, but the new file is a generation away from it.

Should I use a browser or ffmpeg?

Use a browser when you want to see the exact section and finish one clip. Use ffmpeg when you need batch jobs, precise codec settings or repeatable scripts.

How to trim a video

The right method depends on the format you need back. A browser is quickest for one visible cut. ffmpeg is strongest when the output and repeatability matter.

Free toolVideo TrimmerTrim a video in your browser with exact start and end points, a live preview and a local WebM or supported MP4 export.Trim a video

Choose a method

Method	Best for	Output
Browser trimmer	One clip, visual preview, no install	MP4 or WebM when supported
Desktop editor	Multiple cuts, titles, transitions	MP4, MOV or project file
ffmpeg	Scripts, batches and exact codec control	Almost any format

Trim a video in your browser

Open the video trimmer and drop in a file your browser can play. Drag the timeline handles to set the section, or type the times for a repeatable edit. Watch the selection once before exporting.

The browser decodes the selected section and encodes a new MP4 or WebM clip. This is convenient and private, but it is not a byte-for-byte MP4 cut. Keep the original if quality or compatibility matters.

Trim with ffmpeg

For a fast cut that keeps the original streams, use:

ffmpeg -ss 00:01:23.500 -to 00:01:42.000 -i input.mp4 -c copy output.mp4

This is fast because ffmpeg copies the existing video and audio packets. The cut may land on a nearby keyframe. Re-encode when the boundary must be exact:

ffmpeg -ss 00:01:23.500 -to 00:01:42.000 -i input.mp4 -c:v libx264 -c:a aac output.mp4

What changes the quality?

Changing the container or copying packets does not create new image detail. Re-encoding can reduce quality, especially with a low bitrate or several generations. Match the source resolution and frame rate when you export. Keep a master copy before experimenting.

When a browser tool is the right choice

Use the browser for a single short clip, a quick social cut or a file you do not want to upload. Use a desktop editor for several sections or captions. Use ffmpeg for repeatable work and formats the browser cannot write.