Cropping pages and changing page size in PDF by Zaweba
Set crop, trim, bleed and art boxes in millimetres, drag to crop, remove white margins automatically and change page size to fit or centre content.
Pages rarely arrive the exact size you want. A scan has a wide grey border round the paper, a slide export leaves acres of white round each slide, and a document laid out for Letter needs to print on A4. PDF by Zaweba handles all of these from the Pages menu with four related tools: Set page boxes, Crop pages, Remove white margins and Change page size.
They sound similar, but each does a different job. Knowing which one to reach for saves a lot of trial and error.
The four boxes, briefly
Every PDF page can carry several boxes that describe its area. The crop box is the part a viewer shows and a printer normally uses. The trim box marks the finished size after a printed sheet is cut. The bleed box is a little larger, covering artwork that runs off the edge so there is no white sliver after cutting. The art box marks the meaningful content.
Pages > Set page boxes lets you set each of these as margins in millimetres from the edges of the page. That is the tool for print work, where a printer may ask for a file with a set bleed and trim, and for any time you want precise, repeatable margins rather than a rectangle drawn by eye.
Cropping by eye
Crop pages is the quick version. You drag a rectangle over the part of the page you want to keep, and the page is cropped to it. This is the right choice for a scanned receipt sitting in the corner of a large page, a chart you want to send on its own, or a slide where only the central picture matters.
Cropping changes what is shown and printed. It does not cut the hidden content out of the file, so treat it as framing rather than removing. If something must be taken out for privacy, redaction is the proper tool, not cropping.
Letting the app find the edges
Remove white margins trims automatically, looking for the blank space round the content and cropping it off. It is ideal for documents produced by software that pads every page generously, and for reading on a small laptop screen where those margins waste space. Because it works on what is actually on each page, it is quick to apply and then check across a long file.
Look over the result in the thumbnails or the Organise pages grid. A page with a small page number far down at the foot will keep that number, so the trimmed area may be less than you hoped. That is the tool being careful, not failing.
Changing the paper size
Change page size is for the Letter versus A4 problem and similar. You choose a new size and decide whether the content is scaled to fit the new page or centred on it at its existing size. Scaling to fit keeps everything visible and is usually best when the new page is smaller. Centring keeps the content at its true size, which matters for forms and drawings where measurements must stay right, and suits a move to a larger page.
Which tool when
For a printer's specification, use Set page boxes and type the margins they ask for. For a one-off crop of part of a page, drag with Crop pages. For tidying a whole document's empty borders, use Remove white margins. For moving between paper sizes, use Change page size.
It also helps to think about order. Trim the margins first, then change the page size, so you are not scaling up white space. And if you are combining files of different sizes, sort out sizes consistently, either before or after combining, so the final document does not jump between widths as you scroll.
Cropping is not deleting
The biggest is cropping something you meant to delete. Cropped content is still in the file and can be recovered by anyone who resets the crop box. For anything sensitive, redact it.
Another is scaling a technical drawing or form to fit without thinking. If someone will measure from the page or write in boxes of a set size, centring keeps it true.
Last, check a printed proof when the job matters. Boxes and sizes are exact, but only paper shows you how a crop feels in the hand. With those habits, these four tools turn awkwardly sized pages into tidy ones in a few minutes.
