Most PDFs are designed for A4 or Letter paper, with generous white margins around the text. On a phone or e-reader, those margins shrink everything: the screen shows the whole page, including the empty edges, and the text becomes too small to read without zooming and scrolling sideways.

Cropping the margins fixes that. The page gets smaller, so the text fills more of your screen and appears larger.

How much difference does it make?

A typical A4 page has margins of 2 to 2.5 cm on each side. Cropping them removes about a quarter of the page width, so text appears roughly 25 to 30% larger on screen. For academic papers and books with wide margins, the difference can be even bigger.

Step by step

  1. Open Crop PDF and add your PDF.
  2. Click Detect white margins. The tool finds where the text begins and ends and fits the crop box around it, leaving a small border.
  3. Check the box. If headers, footers or page numbers have been cut and you want to keep them, drag the edges outward. If you want to remove them, drag the edges inward.
  4. Use the page menu to check a few other pages, especially ones with wide tables or images.
  5. Keep “All pages” selected and click Crop PDF.

Tips for books and papers

  • Check left and right pages. Some books have wider inner margins, so odd and even pages are shifted. Choose a crop box that suits both, leaving a little extra space on each side.
  • Watch out for wide figures. If one page has a wide table or diagram, make sure the crop doesn’t cut it off.
  • Remove blank pages with Remove Pages, and fix sideways pages with Rotate PDF.
  • Read in landscape on a phone for two-column papers, after cropping.

Cropping scans

Scans often have dark edges, shadows or part of the scanner lid around the page. Crop PDF trims them so the page looks clean. If only one page is crooked or badly placed, pick that page in the preview and choose “Only the page shown”.

Important: cropping hides, it doesn’t delete

Cropping works like a picture frame. The content outside the crop box is hidden from view, but it’s still inside the file, and some PDF editors can show it again. That’s fine for margins, but don’t use cropping to remove private information such as account numbers or signatures. To remove sensitive content, delete the page with Remove Pages, or edit the original document before creating the PDF.

Because the hidden content is still there, cropping doesn’t make the file smaller. If you need a smaller file, use Compress PDF afterwards.

Sending to a Kindle or e-reader

Once cropped, transfer the PDF to your device as usual: by USB, email-to-device, or your e-reader’s app. You’ll find the text noticeably bigger and easier to read. Cropping is done in your browser, so your books and papers aren’t uploaded anywhere.