Question 1

What does cropping a PDF actually do?

Accepted Answer

It adjusts the PDF's CropBox — the rectangle viewers use to decide what part of each page to display and print. The original content stays inside the file, but it's hidden outside the crop area. Most PDF readers, browsers, and print drivers respect the CropBox.

Question 2

Is the cropped-out content actually deleted?

Accepted Answer

No. CropBox is metadata; the original content remains in the file and can be revealed by editing the CropBox back to the full page size. If you need to permanently remove cropped content, that requires a different tool (PDF flattening or re-rendering).

Question 3

Can I set different crops for different pages?

Accepted Answer

Not in this tool — the same margins apply to every page. That's the most common need for cleaning up scans or trimming consistent letterhead whitespace. If you need per-page cropping, split the PDF first, crop pieces separately, then merge.

Question 4

What units are supported?

Accepted Answer

Millimeters (mm), points (pt), and inches (in). All measurements are converted internally to PDF points (1 in = 72 pt) before being applied to the CropBox.

Question 5

Is my PDF uploaded anywhere?

Accepted Answer

No. The crop runs entirely in your browser using pdf-lib. Your PDF, the cropped output, and any intermediate state never leave your device.

Question 6

What happens if my margins are too large?

Accepted Answer

If the requested crop would leave zero or negative area on a page, that page is skipped (left uncropped) rather than producing an invalid PDF. You'll see a preview of the resulting cropped size — if it's negative, dial the margins down.

Crop PDF Margins

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