Crop PDF

Cropping a PDF doesn't touch the pixels or content of a page at all — it adjusts the page's crop box, the coordinate boundary that defines what's visible and printable within a larger media box. Content outside the new boundary isn't deleted, just excluded from view, which is a fundamentally different mechanism from the rasterizing tools like Compress or Grayscale that actually rewrite pixel data.

That makes it well suited to trimming excess white space left by a scanner, cutting off a repeated header or footer strip that runs across every page, or isolating a smaller region of a scanned book page for a cleaner read. Because the same margins are applied uniformly across the whole document, it works best when every page shares a similar layout.

Since the underlying content stream is never modified, cropping doesn't reduce file size — a heavily cropped page can still contain just as much image or text data as before, simply displayed within a smaller frame. It's also worth knowing that a small number of tools or older viewers that ignore the crop box can still expose content technically outside the visible area, so cropping isn't a reliable way to redact sensitive information — for that, content needs to be genuinely removed, not just hidden from view.