Crop Video Online

Crop away unwanted edges

Cropping is useful when a recording includes extra desktop space, black borders, private details or a subject that should be centered before sharing. Instead of opening a full editing suite, you can enter a rectangle in pixels and create a new MP4 that contains only that region. This is handy for screen recordings, tutorials, camera clips, vertical excerpts from horizontal footage and quick social previews that need a tighter frame.

The tool keeps the workflow local. The selected video is written into ffmpeg.wasm inside your browser, the crop filter is applied there and the resulting MP4 is downloaded directly. No server receives the input or output. That privacy-first approach is helpful when the video contains work material, customer information, unreleased visuals or personal footage.

How to choose crop values

The x and y values start from the top-left corner of the original video. A larger x value moves the crop box to the right, and a larger y value moves it down. Width and height define the size of the remaining picture. If you do not know the exact numbers, start with a wider crop, check the download and adjust. Many video encoders prefer even dimensions, so this tool encourages whole pixel values and defaults to an even 16:9 rectangle.

Processing notes

Cropping changes the picture, so the video must be re-encoded. That can take longer than stream copying, especially for high-resolution or long clips. The first crop may also pause while the WebAssembly engine downloads. Keep the original file until you have confirmed that the new frame includes everything important and that text or fine details still look clear after encoding.

Worked example

Imagine a 1920×1080 screen recording where only the application window matters. The window starts 200 pixels from the left and 100 pixels from the top and measures 1280×720. Enter x = 200, y = 100, width = 1280 and height = 720, and the output contains exactly that rectangle. To turn a landscape clip into a centered vertical excerpt, use a width of 608, a height of 1080 and an x value of 656, which is (1920 − 608) ÷ 2.

The crop rectangle must fit inside the source frame. If x plus width, or y plus height, is larger than the video, ffmpeg reports an error and no file is produced, so check the original resolution in your media player first. The output is H.264 at CRF 23 with AAC audio at 160 kbps in an MP4 container. Cropping does not rescale the picture; it only removes pixels, so the remaining area keeps its original sharpness.