How to make every page of a PDF the same size on a Mac

Combine a US Letter document with an A4 scan and the pages come out different sizes. On screen they jump as you scroll, and printed they come out uneven. Merging keeps every page at its own size, so the fix is a separate step.

The free way: print to PDF at one size

1. Open the PDF in Preview and choose File > Print.
2. Click Show Details if you only see a few options.
3. Set Paper Size to the size you want, for example A4 or US Letter.
4. Choose Scale to Fit, so pages are shrunk or grown to the new size rather than cut off.
5. Open the PDF menu at the bottom left and choose Save as PDF.

Check the result

• Open the new file and choose Tools > Show Inspector. The page size is listed there.
• Scroll through and look at the edges of pages that changed size. Scale to Fit keeps the whole page, which may leave a thin white border.
• Printing to PDF can drop links and form fields, so keep the original as well.

Letter or A4?

Use the size the reader will print on: A4 almost everywhere, US Letter in the United States and Canada. If you do not know, A4 and Letter are close enough that either prints well with scaling.

With Simply PDF

Merging is free in Simply PDF and adds a bookmark for each file, so the reader can jump between the original documents. To start fresh at one size, its Convert tool makes pictures and documents into A4 or US Letter PDFs.