Solved! Permanently Cropping a PDF in macOS

The problem: 

  • When you crop PDFs in Apple Preview, you get the message: “Cropping a PDF document doesn’t delete the content outside the selection.”

The scenario: 

I had a PDF of a long document (30+ pages) I needed to read for work, so I thought I could save some time by using a text-to-speech PDF reader app for my iPhone and listening to the document as I drove myself to work. The problem was that the document had a long header and footer, so it was annoying to hear it over and over again on each “page turn,” so I cropped the header and footer off the PDF, but despite the fact that I COULD NOT SEE the header or footer when I opened the PDF (either on my computer or on my text-to-speech app), the words must have still been there somewhere in the document because it continued to read them over and over…

The solution:

There’s quite a bit of discussion about this online and most solutions involve cropping the PDF, then converting each page to a TIFF or some other filetype.  The problem with that (in my case) is that it becomes an image rather than text, and even though it looks the same to the human eye, my text-to-speech app couldn’t read any of it in TIFF form.  But I discovered that if I converted the cropped PDF into a PostScript file, it permanently removed the parts I had cropped off while still keeping it as text.  And the best thing is, I could do it all from Apple’s Preview!  Here’s how:

1) Open the PDF you want to crop in Preview

2) Show the Markup Toolbar by clicking the icon in the top of the window

3) Choose the Rectangular Selection tool

4) Create a box around the part of the document you want to keep (in my case, everything but the header and footer)

4.5) If you have a multi-page document, hold Shift and select all the pages in the thumbnail sidebar to crop all pages at once

5) Choose Crop from the Tools menu (or type command-K).  You’ll get this following message, but don’t worry, just press OK.

6) Now your document should look properly cropped.  Go to the File menu and select Print.

7) From the drop-down menu in the bottom-left of the Print dialogue, select “Save as PostScript”

8) Find the PostScript file you just made and open it with Apple Preview.

9) Preview will automatically convert it back into a PDF upon opening, and it will have permanently removed all the stuff that was outside the cropping area.

And that’s it!  Now you have a PERMANENTLY cropped PDF while maintaining its text formatting.