What units are the margins?

Millimetres, trimmed from each edge. An A4 page is 210 × 297 mm, so a 10 mm crop on all sides takes 20 mm off both the width and the height.

Is the file uploaded to crop it?

No. pdf-lib rewrites the crop box in this tab, so the trimmed copy comes back from your own device rather than a server.

Crop PDF

No upload · runs in your browser

Drop a PDF to cropProcessed in your browser. No uploadSelect files No upload · processed locally · auto-deleted

How it works

How to crop a PDF without uploading it

Set how many millimetres to trim from each edge and FernPDF crops every page to match, then downloads the result. Perfect for removing scanner borders or wide print margins.

Cropping runs locally in your browser using the page crop box, so your document is never sent anywhere.

FAQ

It moves each page's crop box inward by the margins you set, so readers and printers show only the trimmed area. The page content underneath isn't deleted, just the boundary that decides what's visible.

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