How to trim
- Choose your video. A strip of thumbnails appears so you can see where scenes change.
- Drag the left and right handles to the start and end, or type the times (minutes:seconds.tenths). You can also play the video and press Start here or End here at the right moment.
- Choose the cut: fast or frame-accurate.
- Press Trim and download the result.
Fast cut: no re-encoding
Compressed video stores a full picture (a key frame) every few seconds and, between them, only the changes. A cut that starts between key frames would leave the first frames with nothing to build on. The fast cut handles this the way professional tools do: it copies the compressed data from the key frame before your start and marks the file so players begin at your chosen time. The result is exactly the original quality, created in a second or two even for long videos. A few players ignore the marker and show the extra second or two before your start; if that matters, use frame-accurate.
Frame-accurate cut
This decodes the frames in your range and encodes them again, so the video starts precisely at your chosen frame and can be played by anything. It takes about as long as compressing the clip and produces a file of similar quality. Use it for clips you will post or share, where a stray frame at the start would look sloppy.
Tips
- Trim before you compress: a shorter clip fits a size limit at higher quality.
- For a GIF, trim to a few seconds and use the video to GIF tool, which has its own range selection.
- To pull out just the sound of a section, trim it first and then use video to MP3.
What decides a video's file size
A video file is mostly its bitrate (how many bits are spent per second) multiplied by its duration. A 2-minute clip at 2 megabits per second is about 2 × 120 ÷ 8 = 30 MB, plus the sound. Everything else matters only through the bitrate it needs to look good:
- Resolution. 1080p has 2.25 times the pixels of 720p, so it needs roughly twice the bitrate for the same sharpness. Below a certain bitrate, a smaller resolution looks better than a blocky big one, which is why the automatic setting steps down.
- Frame rate. 60 fps needs more bitrate than 30 fps; for talking, screen recordings and most phone clips, 30 or even 24 fps is plenty.
- Movement and detail. A static screen recording compresses far better than handheld footage of a crowd, confetti or water. Two videos of the same length and settings can differ several-fold in size.
- Codec. H.264 plays everywhere. VP9, HEVC (H.265) and AV1 give the same quality in 30 to 50% fewer bits but are not supported by every player or upload form.
- Sound. Usually small: 96 kbps stereo is about 0.7 MB a minute. Removing it helps only for very small targets.
Why it is slower than a desktop app, and when to use HandBrake
This tool uses your browser's own video encoders through WebCodecs, often the same hardware encoders a desktop app would use, but it runs inside a browser tab with a fraction of the computer's memory and without the tuned encoders desktop apps ship. Short clips are quick; a 10-minute 1080p video can take several minutes on a laptop and longer on a phone. The tool refuses files that are likely to run out of memory rather than failing halfway. For long videos, 4K footage, batches of large files, or precise control over the encoder, use HandBrake, which is free, open-source and much faster for heavy work.
Browser support and troubleshooting
The line at the top of the tool lists the video and audio codecs this browser can encode. Current Chrome and Edge on Windows and Mac handle H.264, VP9 and AV1 with AAC and Opus; Safari adds HEVC; Firefox supports WebCodecs from version 130. If a file will not open:
- "This browser cannot decode…" usually means HEVC (H.265) video, common from iPhones, in a browser without HEVC support. Try Safari or Edge on a computer with hardware HEVC, or convert it on the phone (Settings › Camera › Formats › Most Compatible for future videos).
- "Cannot read this file's format" means an old or unusual container such as AVI, WMV or FLV that browsers cannot read. Convert it with HandBrake first.
- It stops or the tab reloads on long or 4K videos: the tab ran out of memory. Trim the video into parts, close other tabs, or use a desktop app.
- Very slow on a phone or an older laptop: the browser may be using software encoding. Shorter clips and lower resolutions help.
Splitting a long video into parts
To send a long video in pieces, trim it several times: 0:00 to 2:00, then 2:00 to 4:00, and so on, using the fast cut so each part takes seconds. With the fast cut, each part starts at a key frame, so consecutive parts may overlap by a second or two, which is usually better than a gap.
Privacy
Your video never leaves your device. It is read and written in the browser tab; there is no upload, no server-side processing and no account. You can disconnect from the internet after the page has loaded and it still works. Free use has no watermark and covers files up to 500 MB and 10 minutes; the A$9 lifetime licence removes those limits (your device's memory still applies), queues up to 20 files and saves presets.