Free Video Trimmer

Worked example

A 10-minute 1920×1080 screen recording of 480 MB, of which you want 1:30 to 2:30 and 5:00 to 5:30. Type 1:30 and 2:30 into the Start and End boxes, press "+ Add segment", and set the second range to 5:00 and 5:30. The page shows "Total kept: 90.0s", the button changes to "Export joined video", and "Estimated output:" shows about 72 MB, because the estimate is the file size times 90 seconds out of 600. In "Fast & lossless" mode the two parts are copied and joined without re-encoding. Now pick the 9:16 crop: the box becomes 606×1080 (shown as "1920×1080 → 606×1080"), "Fast & lossless" is disabled and "Frame-precise" takes over, because a crop needs a re-encode.

Which settings to use, and the limits

• Pick "Fast & lossless" or "Frame-precise". "Fast & lossless" copies the original streams and keeps the original container and extension, so it is instant with no quality loss, but the cut snaps to the nearest keyframe and can start earlier than you asked. "Frame-precise" re-encodes so the clip starts where you set it. It is slower and slightly lossy: H.264 at CRF 20 with AAC audio at 128 kbps in an .mp4, or, for a .webm source, VP8 with Opus audio at 96 kbps in a .webm.
• Type exact times instead of dragging. The Start and End boxes accept 83.5, 1:23.5 or 1:02:03.5. Next to each are "−1f", "−0.1s", "+0.1s" and "+1f" buttons; one frame step is 1/30 second, because the real frame rate is not known in the browser. The sliders move in 0.05 second steps, and a range is always at least 0.1 seconds long. "Set start to playhead" and "Set end to playhead" take the time from the preview, and "Preview cut" plays just the kept part.
• Keep several parts with segments. "+ Add segment" adds another kept range; everything between the segments is cut. Select a segment to edit it, reorder with the arrow buttons, or remove it with the cross. Under "Output", "Join into one video" gives one file named like "name_trimmed.mp4", and "Separate files" gives "name_part1", "name_part2" and so on, with "Download all as ZIP".
• Crop to a vertical or square frame in the same pass. "Crop / aspect ratio" offers 9:16, 1:1, 16:9, 4:5 and "Free", with "No crop" to turn it off. Drag the box to move it and a corner to resize it. Cropping always uses "Frame-precise", and the output size is rounded down to even numbers.
• Know the file limits. The tool takes one video at a time. It refuses a file above about 2 GB on a normal computer, 1 GB on a computer reporting 4 GB of memory or less, and 400 MB on a phone, and shows a caution above 800 MB, 400 MB and 150 MB respectively. The video is read from disk without being copied into memory. The first use downloads the media engine, about 31 MB, which is cached afterwards. Your video is processed in the browser and is not uploaded.

Common problems and how to fix them

It says "Canceled." and nothing was exported.

That notice follows pressing "Cancel" during a trim. Cancel stops the encoder so a long Frame-precise job can be escaped; the "Cancel" link only appears once the encoder has loaded and the work is running. Press "Trim video" again. The engine reloads from the browser cache, which is quick.

It says "Fast mode had to start at the previous keyframe, so the clip is 12.4s instead of 10.0s."

Fast & lossless can only start a copied clip on a keyframe, and screen recordings and downloaded videos can have keyframes many seconds apart. Press "Re-cut frame-precisely" beside the message, or choose "Frame-precise" and trim again. The success line shows the measured length of the exported file, and turns amber when it differs from the length you asked for by more than 0.5 seconds.

It says "Your browser can't preview this file (unsupported codec), but trimming may still work — enter the start and end times in seconds below."

Your browser could not read the file's length within 8 seconds or could not decode it, so there are no sliders or preview. Type the times into "Start (seconds)" and "End (seconds)" and press "Trim video". Crop is not offered in this state, because the frame size is unknown.

It says "This file is 2.6 GB, which is too large to process in your browser on this device (limit ~2 GB). Try a smaller file or trim a shorter clip first."

The numbers in the message are your file and your device's limit: about 2 GB, 1 GB or 400 MB as listed above. Try a desktop computer, or reduce the file with another tool first. Files above the lower "caution" size still run, but may be slow or run out of memory.

It says "This video is in AV1 format, which the in-browser video engine can't decode. Save or download it as MP4 (H.264), then add it again."

Frame-precise and crop have to decode the video, and the engine cannot decode AV1. "Fast & lossless" copies the video without decoding it, so switch to that if you do not need a crop or an exact start. Otherwise convert the clip to H.264 first.

How it compares

The two modes trade speed for accuracy. "Fast & lossless" is instant and keeps the file exactly as it was, but you cannot choose the exact start frame. "Frame-precise" starts exactly where you set it, at the cost of a re-encode, and it has no quality or bitrate setting: the quality is fixed at H.264 CRF 20 (or VP8 for WebM). Compared with a desktop video editor, this tool only cuts, joins and crops one video at a time. It has no transitions, titles or audio editing, and a very large file can hit the limits of browser memory. In exchange there is nothing to install.