How to crop a PDF: trimming scan margins, headers and footer noise
Scanners are generous: they capture the desk edge, a finger of shadow, three-hole-punch margins and every stray pencil mark near the border. On screen this is cosmetic clutter; in print it shrinks the useful area, and in a stack of 200 scanned pages it makes every page slightly harder to read. Cropping removes that border once, for the whole document, without touching the content inside.
This guide walks through how percentage cropping works, when to crop specific pages instead of all of them, and what the method cannot do. The Paperly tool is honest about its approach: it adjusts page geometry, it does not erase or redraw content, and it never uploads your file.
What percentage cropping actually changes
The tool expresses each trim as a percentage of the page dimension — not of centimeters. Ten percent on the left of an A4 page (210 mm wide) removes 21 mm; the same 10% on a US Letter page (216 mm) removes about 21.6 mm. Percentages make the tool page-size agnostic: a mixed-size document gets proportional trims on every page.
- Left / Right trims are percentages of the page width.
- Top / Bottom trims are percentages of the page height.
- Each edge accepts 0–40%, so the heaviest possible combined trim leaves 20% of the original page.
- Set an edge to 0 to leave it untouched — most jobs only trim one or two edges.
Content inside the remaining area is untouched. Nothing is scaled, stretched or redrawn — the page simply becomes smaller, exactly like trimming a photograph with scissors.
Finding the right percentages
- Open the PDF and note what occupies the borders: shadow width, margin text, hole punches.
- Estimate each unwanted band as a share of the page — a 20 mm shadow on A4 width is roughly 10%.
- Start conservative: trim 5–8% per affected edge and inspect the result.
- Increase an edge only if content still peeks through; overshooting cuts real content and cannot be undone inside the cropped file.
Cropping removes geometry, not pixels — but the removed band is gone from the output. Keep the original file until you have verified the crop on a few representative pages.
Cropping only some pages
The pages option accepts ranges like "1-3, 5". Leave it empty and every page is cropped; fill it and only the listed pages change. This matters when a document mixes page types — for example a report whose scan pages need 12% trimmed but whose added spreadsheet pages are already tight.
- Use a single range for a contiguous block: 1-8.
- Combine ranges and singles for scattered pages: 1-3, 7, 12-15.
- The same percentages apply to every listed page — the tool does not support different trims per page in one pass. Run the tool twice with different settings if pages need different treatment.
The classic scan-cleanup workflow
Most crops happen right after scanning, and they chain well with the rest of the toolbox:
- Scan the stack; the PDF arrives with borders, shadows and hole punches.
- Crop PDF — trim 8–12% from the edges that carry scanner noise.
- Deskew or clean further if needed, then run OCR so the text becomes searchable.
- Add page numbers or Bates numbers to the clean pages — stamps sit better when the margin is tidy.
Doing the crop before numbering is the right order: numbers drawn into a footer you later crop away would be lost.
What cropping cannot do (honest limits)
- It cannot remove content in the middle of a page — only edge bands. A logo floating mid-page needs the Whiteout or Edit Text tool instead.
- It cannot apply different trims to different pages in one pass — run the tool multiple times with page ranges.
- It does not reduce file size meaningfully on its own — the images remain at their original resolution. Follow with Compress PDF if the goal is a smaller file.
- It cannot rotate pages — use Rotate PDF for orientation problems.
Cropping before or after other tools: an ordering guide
Crop changes page geometry, and several other tools care about geometry — so the position of the crop step in a workflow matters. A short ordering map covers the common cases:
- Crop before page numbers and Bates numbers — stamps drawn into a footer you later trim would be lost with it.
- Crop before OCR — trimming scan borders first removes noise lines that OCR might misread as characters.
- Crop before converting to Word or Excel — cleaner geometry produces cleaner text extraction downstream.
- Crop after merging — merging does not change pages, but cropping one merged file is one pass instead of many.
- Compress last — compression re-encodes the final content, so any geometry change before it is captured in one optimized result.
The general rule: geometry first, content second, optimization last. Following it keeps each tool operating on the version of the document it handles best.
Troubleshooting
- Content is cut off — a trim went too deep. Re-crop from the original file with smaller percentages; the cropped file no longer contains the removed band.
- Pages came out different sizes — the source had mixed page sizes and each was trimmed proportionally. Normalize sizes first with the Resize tool if uniformity matters.
- Nothing seemed to change — percentages may be too small to notice at zoom, or the wrong edge was set. Verify on one page at 100% zoom.
- The cropped PDF prints with unexpected margins — printer scaling may add its own fit-to-page margin; check the print dialog settings.
Related tools that pair well
- Compress PDF — shrink the file after cropping (cropping alone barely changes size).
- OCR PDF — make a scanned, cropped document searchable.
- Add Page Numbers — number the clean pages once the margins are final.