A4 and US Letter are the two common page sizes, and they are close enough to confuse but different enough to cause trouble. A4 is 210 by 297 mm; US Letter is 215.9 by 279.4 mm, the same as 8.5 by 11 inches. Letter is wider, A4 is taller. Pick the one your printer is loaded with, and set the same size in your print dialog.
Every maker on this site offers both, so the choice is simply about what comes out of your printer.
The exact sizes
| Size | Width | Height | Used in |
|---|---|---|---|
| A4 | 210 mm | 297 mm | Most of the world |
| US Letter | 215.9 mm (8.5 in) | 279.4 mm (11 in) | US, Canada |
The gap is small. Letter is about 6 mm wider and 18 mm shorter than A4. You will not notice it on a page of plain text, but you will on anything where the layout has to line up with the paper edges.
Which one to choose
The rule is simple: use whatever your printer holds.
- In the United States or Canada, that is almost always US Letter.
- Nearly everywhere else, it is A4.
If you are sending a file to someone in another country, ask which size they print on, or send both. A document built for A4 and printed on Letter, or the reverse, will either lose a strip of content or get rescaled.
Why the mismatch causes problems
When a printer is handed a page the wrong size, it does one of two things, and neither is ideal:
- It clips. An A4 layout on Letter paper loses about 18 mm at the bottom, which can cut off a footer, a signature line or the last row of a calendar.
- It rescales. If “fit to page” is on, the whole page shrinks or stretches to fit. For text that is harmless, but for graph paper or anything measured, the squares no longer match their stated size.
Get it right the first time
Two checks cover it:
- In the maker, pick the size your printer uses.
- In the print dialog, confirm the same size and set scale to 100% or Actual size, not “fit to page”.
Do that and the printout matches the preview exactly. Start with the calendar maker or any other tool, and the page size you choose carries straight through to the PDF.