Crop the margins off PDF pages

Why crop a PDF

Phone scans and flatbed scans rarely line up with the paper. The result is a dark band down one side, a strip of desk at the bottom, or a page surrounded by so much white space that the text is tiny when the file is opened on a phone. Slides exported to PDF often carry a wide border, and documents printed to PDF sometimes include a header with a URL and a date that nobody wants. Cropping removes all of these and makes the content fill the screen or the paper.

Detecting margins automatically

Detect margins looks at the page in the preview, finds the outermost marks that are not white, and sets the four margins to just outside them, leaving a small border so letters at the edge are not cut. It works best on clean pages. On a scan with a dark edge it will treat the edge as content; in that case, type the margin on that side yourself. Each page can be previewed with the arrows, so check a few before you crop the whole document.

When pages differ — a pile of scanned receipts, or a document that mixes A4 and Letter — one set of margins will not suit them all. Tick Auto-crop instead, and each page is cropped to its own printed area. Blank pages are left alone.

Odd and even pages

A scanned book has its spine on the left of odd pages and on the right of even ones, so the wide margin swaps sides. Crop odd pages first, download, then load the result and crop even pages with the margins mirrored. The same applies to documents printed for double-sided binding.

What cropping does, and does not do

Cropping tells PDF readers and printers which part of each page to show. Text, images and vector drawings stay sharp, and the file size barely changes. But the content outside the new edges is still in the file; it is simply not displayed. That makes cropping useless for hiding private information, such as an account number in a header. Use Redact PDF for that, which removes it for real.

If you need every page to be a standard size after cropping — A4 for an upload form, for example — run the cropped file through Resize pages.