Video Trimmer

Why trim a video losslessly

Most of the time you do not need to edit a video — you just need a shorter piece of it: the 30 seconds a client asked to review, the highlight from a long screen recording, or a clip with the dead air at the start and end removed. The fast, correct way to do that is a lossless trim: copy the exact span you want out of the file without touching the picture or the sound.

This trimmer does precisely that. You give it a start time and an end time (or a start time and a duration), and it copies the original audio and video packets straight into a new file. There is no decode-and-re-encode step, so three things are true at once: the cut is near-instant (even a 40-minute upload trims in moments), the result is bit-for-bit identical to the source for the part you kept, and the output stays in the same format as the input. Nothing is re-compressed, so you never stack a second round of compression artefacts onto footage that was already encoded once.

Lossless stream-copy trim vs a re-encode trim

Most editors and many online cutters re-encode the whole clip when they trim. That is slower and throws away a little quality every time. Here is the trade-off side by side:

The only thing you give up for that speed and quality is frame-exact cut points, which is where keyframes come in.

Why your cut can start a moment early (keyframes)

Compressed video does not store every frame in full. It stores occasional complete frames — keyframes (also called I-frames) — and then, in between, stores only what changed. A frame in the middle of that run cannot be decoded on its own; it depends on the keyframe before it. Because a stream copy does not decode anything, it can only start the new file on a keyframe. So when you ask to start at, say, 0:30, the tool seeks to the nearest keyframe at or before 0:30 and begins there.

Worked example: suppose your video has a keyframe every 2 seconds (0:28, 0:30, 0:32, …) and you set the start to 0:31. The trim begins from the 0:30 keyframe — about one second early — because that is the last fully-decodable frame before your start. The end point is not affected the same way. This is normal for any lossless cutter; if you need the cut to land on an exact frame, that requires a re-encode (a possible future option, but out of scope here). For almost every review-clip and social-cut use case, a fraction of a second at the head is a fair price for an instant, no-quality-loss trim.

What you can trim

Upload an MP4, MOV, M4V, WebM, MKV or AVI file. The trimmer reads the real streams in the file (not just the extension), so a mislabelled or audio-only file is rejected with a clear message rather than producing a broken clip. The output container and codecs always match your input. Enter times as MM:SS or HH:MM:SS — for example 0:30 and 1:45, or 1:02:10 for a long recording. Leave the end at the very end and the clip is trimmed to the last frame.

Limits and privacy

Because the work is a cheap stream copy rather than a full transcode, the limits are generous: without an account you can trim a file up to 200 MB and 20 minutes; a free account raises that to 500 MB and 60 minutes. You can trim one file per run. Your upload is processed securely, is never shared, and both the upload and the trimmed output are deleted automatically shortly after processing — no account is required to use the tool.