How to crop PDF margins online for free
Crop PDF margins in millimetres on selected pages. Try a 5 mm example, follow Mac browser steps and understand why cropping is not secure redaction.
Use Crop PDF to reduce visible margins on selected upright pages. Enter how many millimetres to trim from the top, right, bottom and left. The tool runs on your device without a document upload or account.
Start with a small, measured crop
- Keep the source PDF and open a working copy within 50 MB. The PDF must be valid and unencrypted.
- Enter Pages such as
1to test one page, or leave it blank to apply the crop to every page. - Set each margin separately. For a gentle test, enter
5mm on each edge rather than guessing a large crop. - Select Crop PDF, inspect the preview and download the result.
- Open the saved PDF in your usual reader. Check headings, page numbers, side notes and content near every cropped edge.
Values are measured inward from the current visible page boundary. Top and bottom trims must leave some visible height, and left and right trims must leave some visible width. Pages must be upright; this tool does not normalize an existing rotation setting.
Try the 5 mm example
Compare our two-page synthetic source PDF with the 5 mm cropped result. We trimmed 5 mm from all four edges of both Letter pages. Each visible page changes from 612 × 792 points to about 583.65 × 763.65 points. The page count remains two and the example's text stays inside the visible area. The underlying media box stays 612 × 792 points. Inspect the crop-box measurements.
How to crop a PDF on Mac
Open the same browser tool on your Mac, select the PDF from your device and follow the margin steps above. Save the downloaded copy to a clear location and open it in your preferred reader. This is a browser workflow; it does not require an Acrobat subscription or install a desktop app.
Manual crop versus automatic border removal
This tool uses numeric margin values. It does not automatically detect white borders, remove blank pages or offer a drag-to-select crop rectangle. Uneven scans can need different values on different page ranges. Start with one page, then process another range in a separate working copy if needed.
Cropping hides content; it does not erase it
Text and images outside the crop boundary can remain in the file. A different viewer or editor may reveal them. Do not use cropping to hide a name, account number or confidential paragraph; follow a proper redaction workflow instead. Cropping also does not guarantee lower file size.
When another layout tool fits better
If you need A4 or US Letter pages, resize the paper dimensions. If one scanned page contains two facing pages, use Halve PDF Pages. For multiple source pages on one printed sheet, use N-up PDF.
Rewriting a document can invalidate signatures. Retain originals and verify the entire saved copy before sharing.
Prepared by PDF Tools Club · Updated October 18, 2026. Instructions reflect this release’s controls and limits.