Crop PDF margins so pages read larger on a phone or e-reader

The tool does not cut anything out of the file. It sets each page's crop box, which is the rectangle a PDF reader displays. Everything outside that rectangle is still stored in the file, so the download is about the same size as the original, the text stays searchable, and anyone with PDF software that resets the crop box can see the trimmed area again.

That makes cropping safe to experiment with, and useless for hiding anything. If a margin holds a name, an address or a handwritten note you do not want seen, cropping is not the right tool; the content is still there.

Pages that were rotated with a /Rotate flag are handled as you see them. The Top, Right, Bottom and Left values refer to the page as it appears in the preview, and the tool turns them back into the page's stored orientation for you.

After you add a PDF, the preview shows the first page under the line Drag on the page to draw the area you want to keep. Drag across it and the parts you are trimming darken while the kept area gets a bright border. If you would rather be exact, the four fields Top (%), Right (%), Bottom (%) and Left (%) take a percentage of the page for each side, capped at 95. Trim 5% all round is a quick starting point for a light trim, and Reset crop clears everything.

The preview shows one page at a time, and the same box applies to every page you crop. Use Previous and Next to step through the document before you run it. Look for the page with the widest text block, a figure that runs close to the edge, and a page with a header or page number, since those are what a tight box cuts off first.

Percentages are relative to the page as it is now. If you crop a file, then crop the result again, the second set of numbers is measured against the already-trimmed page, not the original.

Scanned books usually have mirrored margins: the gutter sits on the right of odd pages and on the left of even pages. One box cannot fit both. Under Crop these pages, choose Chosen pages and enter the odd pages as a range such as 1-3, 5, 8-10 (the word last means the final page), set margins that suit them, and click Crop pages. Then add the downloaded file, select the even pages, enter the mirrored margins, and run it again.

The same two-pass approach works for a document where a cover or an appendix has a different layout from the body. Pages you leave out of the selection keep their original crop box.

Reader apps scale the visible page to the screen width, so a tighter box directly means bigger text. Leave a small margin rather than trimming right to the ink; letters that touch the screen edge are harder to read than a hairline of white space.

For printing, the cropped page is smaller than the paper, so choose Fit to page or Scale to fit in your print dialog. The printer then enlarges the kept area to fill the sheet, which is the whole point of trimming.

Cropping does not reflow text. A two-column article stays two columns, and small type stays small type inside a smaller frame.

Crop PDF takes one PDF at a time. Drop several and the first is kept while the rest come back with a note that only one file can be used at a time. A file can be up to 100 MB, and anything over 50 MB brings a warning that large files are held entirely in memory and may struggle on a phone.

The Crop pages button stays off until a PDF has loaded, the page selection parses, and the box still keeps something. If Left plus Right reaches 95 percent, or Top plus Bottom does, the button simply never turns on, so you trim less rather than meeting an error.

Keep the original file. Because cropping is reversible only with software that edits the crop box, having the untouched copy is the simplest way back if you trim too much.