Why crop a PDF at all?
You scanned a paperback page and got two inches of grey scanner bed around the actual text. Or you exported slides and every one carries a thick white border that wastes ink and screen space. Cropping shaves those edges off so the content fills the page.
This trims the margins of every page in one pass. Upload a file, tell it how much to cut from each edge, and download the result. The page count shows up the moment your file loads, so you know exactly how many pages are about to change.
Here’s the part that matters for anything sensitive: your PDF never leaves the machine. The crop happens with pdf-lib running in your own browser tab. Nothing gets sent to a server, nothing sits in an upload folder, nothing to delete later. Close the tab and it’s gone.
How the cropping works
Every PDF page carries two rectangles that control what you see. The MediaBox defines the full sheet. The CropBox defines the visible window inside it. This tool insets both by the margins you set, so viewers and printers show only the trimmed region.
It works by adjusting boxes, not by deleting content. That’s worth knowing. The text and images outside the new crop are still in the file, just hidden past the edge. For most uses that’s perfectly fine. If you need the trimmed pixels gone for good, flatten or re-export the PDF afterward.
You pick the unit too. Millimeters if you think in paper sizes, points if you think in typography (72 points to the inch). A 10 mm cut on an A4 page knocks roughly 28 points off each chosen side.
Steps
- Drop your PDF onto the box, or click to browse.
- Choose millimeters or points.
- Go uniform with one margin for all four sides, or switch to per-side and set top, right, bottom, and left separately.
- Hit Crop PDF.
- Download the trimmed file.
A few things worth knowing
Margins apply to all pages equally. If page 3 has a wider border than the rest, a single uniform value can’t fix just that one page. Crop conservatively, check the result, crop again if needed.
Don’t go overboard with the numbers. Ask for margins bigger than the page itself and there’d be nothing left, so the tool stops you before it produces a blank document.
Scanned PDFs vary page to page. Feeder scanners drift, and one sheet may sit a millimeter off from the next. Pick a margin that’s safe for the worst page rather than perfect for the best one.
Rotated pages stay correct. The crop reads each page’s real box first, so a landscape page mixed into a portrait document gets trimmed on the right edges, not scrambled.
FAQ
Does my file get uploaded anywhere? Nope. Everything runs locally with pdf-lib inside your browser. The PDF stays on your device the whole time.
Can I crop each side by a different amount? Yes. Switch to “Per side” and you get four boxes: top, right, bottom, and left. Leave any at zero to keep that edge as-is.
Will cropping shrink the file size? A little, usually not much. Cropping hides content past the new edges rather than stripping it out, so the bytes mostly stay. If size is your goal, run it through a PDF compressor instead.
What units can I use? Millimeters or points. One inch is 25.4 mm or 72 points, so a half-inch margin is about 12.7 mm.
Is the cropped text still selectable? Yep. The words inside the visible area stay fully searchable and selectable. Only what falls outside the new crop is hidden.
Does it handle big PDFs? It can, though a 300-page scan will take a few seconds since your browser does all the work. A handful of pages is basically instant.