About Crop PDF
PDF pages often have more margin than they need. A scanned book has wide white borders that waste space when you read it on a phone. A receipt scan has the desk underneath captured along with the receipt. A research paper has half an inch of blank space on each side that prints fine but reads cramped on a tablet.
Crop PDF trims the visible area of each page. The trimmed pages take less screen space when you read them, less paper when you print them, and less attention from the eye for the content that matters.
Cropping with a preview
The preview shows your first page with a draggable rectangle on it. Drag the handles to set the crop area. The numbers update as you drag so you can see how much margin you're cutting off in points.
If you have an exact target, type the margin values in the fields. 36 points is half an inch. 72 points is a full inch. The unit is points because PDFs are designed in points, and using anything else introduces rounding.
You can also use the auto-detect option. It looks at the content of each page, finds the smallest rectangle that contains all the ink, and crops to that with a small padding. Works well for documents with consistent margins.
All pages or specific ones
The default applies the crop to every page. This is what you want for a document with uniform margins.
If pages have different content layouts (a book with a long-format cover page and shorter body pages, for instance), apply different crops to different pages. The page range field accepts "1", "1-5", or "odd" / "even" to scope the crop.
Cropping versus hiding
Cropping in PDFs sets a CropBox, which is the area visible to readers and printers. The underlying content outside the CropBox is still in the file; it's just not displayed.
If you need to actually remove sensitive content outside the crop area, use the Redact PDF tool instead. Redaction permanently removes the data. Cropping just hides it.
For most use cases (better screen reading, smaller printouts, cleaner appearance) cropping is fine. Reserve redaction for when you're sharing a document with sensitive content beyond the margin.
Real scenarios
Preparing a scanned book or journal for tablet reading. Cropping the white borders gives you a noticeably larger reading area without changing the typography.
Cleaning up phone-scanned receipts. Crop out the desk, the floor, the angle of the receipt.
Cropping a slide deck PDF from 4:3 to 16:9 (or the other way) before printing.
Reducing file size as a side benefit. Cropped pages are slightly smaller files because the renderer needs less data per page.
Privacy
Cropping runs in your browser. The PDF stays on your machine and the cropped output is built locally.
Tips designers and document professionals use
When cropping for tablet reading, leave a few millimetres of padding around the content. A crop tight against the text feels claustrophobic on a small screen. A small margin gives the eye a place to rest and lets the reader scroll without the content feeling clipped.
If you're cropping for print, account for the printer's non-printable area. Most office printers can't print all the way to the edge of the page; they leave a 5 to 10 mm margin no matter what your file says. So a crop that goes to the page edge often comes out with empty space at the borders anyway.
For documents with mixed page sizes (a contract followed by a wide appendix table, for instance), crop each section separately using the page range field. A single crop applied to everything either chops the wide pages or leaves white space on the narrow ones.