How to Trim a Video in Your Browser
Load your video
Drag an MP4, WebM, OGG, AVI, MOV, or MKV file onto the upload area or click Choose Video File. The clip loads straight into the on-page preview player and stays on your device, since trimming runs locally with ffmpeg.wasm.
Set the start and end points
Drag the two handles on the timeline to frame the segment you want to keep. The dimmed regions show what gets cut, the tooltips show each timestamp, and the clip duration updates live. Click anywhere on the bar to seek and press play to preview only the selected range.
Pick output and export
Choose MP4 or WebM and a quality level of High, Medium, or Low, then click Clip Video. ffmpeg.wasm loads on first use, re-encodes the selected range with both video and audio, and a Download Clip button appears when it finishes.
Output Format and Quality Options
The clipper re-encodes your selection so you control the container, codec, and bitrate of the result. MP4 uses the H.264 video codec for the widest compatibility, while WebM uses VP9 video with Opus audio for smaller files. Quality maps to ffmpeg CRF values: a lower number keeps more detail and produces a larger file.
| Option | Setting | What it does | Best for |
|---|---|---|---|
| Format | MP4 (H.264) | Most compatible container, plays on nearly every device and editor | General use, phones, social uploads |
| Format | WebM (VP9 + Opus) | Modern codec with smaller files at similar quality | Web embeds and bandwidth-conscious sharing |
| Quality | High (CRF 18) | Near-source detail, largest file size | Archiving or further editing |
| Quality | Medium (CRF 23) | Balanced detail and size, ffmpeg default range | Everyday clips and previews |
| Quality | Low (CRF 28) | Smaller files with visible compression | Quick shares and messaging |
| Audio | Kept | Both video and audio tracks are carried into the output | Clips where sound matters |
Which Settings Should You Choose
Posting to social media
Pick MP4 with Medium quality. H.264 plays everywhere and CRF 23 keeps the file small enough to upload quickly while still looking clean on a phone screen.
Saving a clip to keep editing
Choose MP4 at High quality (CRF 18). The output stays close to the source so you lose little detail when you import it into other editing software later.
Embedding on a website
Use WebM with Medium quality. The VP9 and Opus combination delivers comparable picture quality to MP4 at a smaller size, which helps pages load faster.
Sending over chat
Go with Low quality and a short trim range. Smaller CRF 28 files and a tight start-to-end selection keep the clip under typical messaging size limits.
Common Problems and Fixes
Processing is slow
ffmpeg.wasm runs entirely in your browser, which is slower than a native app, and the tool re-encodes rather than copies the stream. Longer ranges and the High quality setting take the most time. Trim a shorter segment or lower the quality to speed things up.
ffmpeg fails to load
The error about libraries not loaded usually means the page could not download the ffmpeg core, or your browser lacks SharedArrayBuffer support. Check your connection, reload the page, and use an up-to-date desktop Chrome or Firefox.
The tab crashes on a big file
Large videos are loaded into browser memory, so files over roughly 500MB can stall or crash low-memory devices. Trim on a desktop, close other tabs, or shorten the selection so less data has to be held at once.
End time will not move past the start
The handles enforce a minimum gap, so the end point always stays after the start. If a handle feels stuck, drag the other one first, or click an open spot on the timeline to reset the playhead before adjusting.