How to crop a PDF — and what cropping actually does

Scanned pages arrive with three centimetres of grey around the edge. A page printed from a web browser has a header and a URL you did not ask for. A slide deck exported to PDF has bands of nothing at the top and bottom of every page.

Cropping fixes all of these. It is also, in one specific way, not what most people assume it is.

Cropping hides; it does not delete

A PDF page carries more than one measurement of itself. The MediaBox is the full physical page. The CropBox is the region a viewer should display. Cropping a PDF sets the CropBox to a smaller rectangle, and every viewer obligingly shows you only that.

The content outside it is still in the file. It is not painted, and it is entirely recoverable — anyone can reset the CropBox in a PDF editor, and text that has been cropped out will often still be found by a text extraction tool, because the words are still in the page's content stream.

This is not a shortcoming of any particular tool — it is how the PDF format expresses cropping, everywhere, including Acrobat. It is worth knowing because the interface looks exactly like an operation that removes things.

When cropping is exactly right

• Trimming scanner margins so a document fills the page and prints without a grey border.
• Cutting the browser header and footer off a printed web page.
• Removing whitespace so a document reads properly on a phone or an e-reader, which is where wide margins hurt most.
• Standardising a bundle of pages that were scanned or exported at slightly different sizes.
• Cutting a figure or a table out of a page so it can be dropped into a slide.

Doing it

1. 1Open Crop PDF and drop your file in.
2. 2Drag a box onto the page preview. You are drawing the region to keep.
3. 3Choose whether it applies to this page or all of them.
4. 4Download.

Applying one crop to every page assumes the pages are consistent. For a scanned document that is usually true and occasionally not — a page fed in slightly crooked will lose an edge. Check the result rather than assuming, particularly on long scans.

Crop, resize and scale are three different things

• Cropping changes what part of the page is shown. The content stays the same size and some of it stops being visible.
• Scaling changes the size of the content on the page. Everything stays visible and gets smaller or larger.
• Resizing changes the paper. The content stays as it is and there is more or less room around it.

The common mistake is cropping when the aim was to fit more on a page. Cropping cuts off the edges; it does not shrink anything. For fitting a wide document onto a printable page, scaling at print time is the answer — and for spreadsheets specifically, getting Excel onto one page is its own problem with its own solutions.

Printing a cropped PDF

Most printer drivers respect the CropBox and print only the visible region, which is what you want. A few older ones print the MediaBox — the whole original page, hidden content and all — which is startling if you cropped something sensitive out.

If that matters, or if you are sending the file onwards, flatten the crop by turning the cropped result into images and rebuilding: PDF to PNG and then PNG to PDF. You lose the searchable text, which is the price, and the hidden content is genuinely gone because it was never drawn into the images.

Common questions

Is the cropped-off content really still there?

Yes. Cropping shrinks the visible page area, which is how the PDF format handles it. Resetting the crop in an editor brings it back, and text extraction may still find cropped-out words. Use redaction if content must actually be destroyed.

Can I undo a crop?

In a PDF editor that exposes the page boxes, yes — the content was never removed. From this tool, simply drop your original in again; it is never modified.

Does cropping reduce the file size?

Almost not at all, and for the reason above: nothing is removed. If the file is too large, Compress PDF is the tool for that.

Can I crop each page differently?

Yes — apply a crop to a single page rather than all of them, and repeat. Worth doing on documents that mix portrait and landscape pages, where one rectangle cannot suit both.

Why does my cropped page still look off-centre?

Usually because the original scan was skewed, so the content is not square to the page and no rectangular crop can make it look centred. Straightening it first is the fix — Scan to PDF deskews pages, and rotating handles pages that came in at ninety degrees.