What 148 × 210 mm means
A5 is a finished paper size. It does not identify a ring pattern, disc pattern, printable area or binding system.
The builder preserves these finished dimensions and will not silently scale the page to make an incompatible imposition fit.
Choose the paper you print on and the binding margin
Print on 148 × 210 mm A5 paper, or centre one page on A4 or US Letter. Two pages per sheet works on A4 turned sideways, because each half is 148.5 × 210 mm. It doesn’t work on Letter, because each half is 139.7 mm wide, narrower than the 148 mm page, so the builder won’t offer it rather than shrink the page.
Centred and two-to-a-sheet files include crop marks where there is room outside the page. Where the edge of the paper is already the edge of the page, there is no mark; the page size stays the same.
The content margin moves the writing area away from the binding edge. It is space, not a hole position, and it cannot promise that a particular punch fits. Trim first, then line the page up with your punch’s own guide.
Print one test page first
Print one test page before the whole set. In the print dialog, choose the paper the PDF is made for, turn off Fit to page and any other scaling, and measure the test mark. The PDF is the right size; the printer settings decide whether it stays that way.
After trimming, measure the width and height before you punch. If they are off, fix the print size setting or the paper you chose; don’t guess a new page size to make up for it.
Binding and punch pattern
Filofax punches its A5 refills, 210 × 148 mm, with six holes. Other A5 binders can space their rings differently, so check against a page you already use.
The PDF leaves writing clearance. It does not print a hole template.