Crop PDF

How to crop a PDF

1. Drop a PDF file on the drop zone, or click it to choose one. The first page appears under Preview.
2. Under Margins to remove, choose the Unit (Millimetres (mm) or Points (pt)) and enter how much to trim from the Top, Right, Bottom and Left. With Same value on all sides ticked, typing in one field fills the other three; untick it to set each side separately.
3. Watch the preview: the dashed frame shows the area you keep and everything outside it is darkened. The line above the preview gives the page size before and after cropping. Use the arrows or the page number to check other pages.
4. Under Apply to, keep All pages or choose Only these pages and type them, for example 1, 3-5.
5. Optionally tick Also change the page size (MediaBox) (see below).
6. Click Crop PDF, then Download. The file is named after the original, for example slides_cropped.pdf.

Margins are measured on the page as you see it. On a page stored sideways and displayed in landscape, Top still means the top of what you see.

Cropping hides content, it doesn’t delete it

A PDF page has several boxes. The MediaBox is the full sheet; the CropBox is the part that viewers show and print. This tool sets a smaller CropBox, exactly like the crop function of desktop PDF editors. Everything outside it becomes invisible, but it is still in the file: the text, images and drawings in the trimmed margins are not erased, and anyone can restore them by resetting the crop box in a PDF editor. Text that runs under the edge can often still be selected or found by a search.

So cropping is the right tool for removing white space, scanner borders or printer marks, and for making slides or articles easier to read on a small screen. It is not a way to hide confidential information. To remove something for good, you need a redaction tool that deletes the underlying content.

For the same reason, cropping doesn’t make the file smaller.

CropBox or MediaBox?

By default only the CropBox changes, which is what every PDF reader follows and the safest choice. Some printers, imposition software and older tools ignore the CropBox and use the full sheet. Ticking Also change the page size (MediaBox) sets both boxes to the cropped area, so these programs see the new page size too. The content outside is still stored in the file in either case.

Units and limits

1 mm equals about 2.83 points, and 1 point is 1/72 of an inch. Switching the Unit converts the values already entered. The same margins are applied to every selected page, so pages of different sizes all lose the same amount. The tool refuses margins that would leave less than 10 pt (about 3.5 mm) of a page, and tells you which page is too small.