PDF Crop narrows the visible area of a page: cutting the black or white border off a scan, or boxing the part of an A4 page that actually holds content, so a reader or an e-reader stops showing a wide margin. It does this by rewriting the crop box (CropBox) of each page — a reader shows only what is inside the box, while what lies outside stays in the file.

So it is a crop at the display layer: the file does not get smaller, and nothing cropped away has been deleted — it is simply no longer visible.

1. 01Draw the area— click “Select crop area”; the dialog shows the first page of the file as a reference, and you drag out the rectangle to keep. The panel reports “Selected: xx% wide × xx% high (relative to the page)”.
2. 02Choose the pages it applies to— “All”, “Selected (N)” or “Range”; a range is written like 1-3,5,8-, or click “Selected pages” to fill in the pages already chosen in the middle area.
3. 03Crop and download— click “Crop and download” to get <original-name>_cropped.pdf. To change the area, click “Select the area again”.

Input

standard PDFs; an encrypted file needs its password removed with “PDF Unlock” first

Reference page

the box is drawn on the first page (or the first page that renders) and applied to the target pages as a relative ratio; if pages differ in size or in where the content sits, the cropped area differs too

Display-layer crop

only the CropBox changes, so content and file size stay the same; a few printing or reprocessing tools work from the MediaBox instead and may show the cropped-away part again

Rotated pages

a page carrying a rotation attribute is cropped in the direction you see in the preview, with no conversion needed on your side

What it does not do

it does not delete what is outside the box (for privacy work, use “PDF Redact”), does not reduce the file size (use “PDF Compress”), and does not detect the content boundary automatically

Preview rendering and the crop-box write both happen locally in the browser and the file is not uploaded.