Letter or A4: paper sizes for calendars
The two sizes are close enough to look interchangeable and different enough to spoil a print. This page is the practical version: which one you have, what happens when they are mixed up, and how to print a calendar so it comes out at its true size.
The two sizes, side by side
| Size | Millimetres | Inches | Used in |
|---|---|---|---|
| Letter | 215.9 × 279.4 | 8.5 × 11 | United States, Canada, Mexico, the Philippines, much of Latin America |
| A4 | 210 × 297 | 8.27 × 11.69 | Nearly everywhere else — Europe, Asia, Africa, Oceania |
| Legal | 215.9 × 355.6 | 8.5 × 14 | US legal documents; rarely right for calendars |
| A5 | 148 × 210 | 5.83 × 8.27 | Half of A4 — desk planners and notebooks |
Letter is wider and shorter; A4 is narrower and taller. The mismatch is about 6 mm in width and 18 mm in height — invisible on screen, obvious on paper.
What the A series gets right
A4 belongs to the ISO 216 family, built on one elegant property: every size has the same width-to-height ratio, 1:√2. Cut an A4 sheet in half and you get two A5 sheets of exactly the same proportions; double it and you have A3. That is why European photocopiers scale between sizes losslessly. Letter has no such relationship to anything — it is simply the size American paper settled on.
What goes wrong when they are mixed
- An A4 design printed on Letter is 18 mm too tall: the printer either cuts the bottom row of the calendar off or shrinks everything to fit.
- A Letter design printed on A4 leaves a lopsided white strip and shifts the margins the design was balanced around.
- "Fit to page" hides the problem by silently rescaling — the calendar prints, but smaller than designed, with hairlines thinned and boxes shrunk.
The fix is unexciting: generate for the paper in the tray, and print at 100% / Actual size. Calendarloom builds the PDF at the exact physical size of the paper you choose, so no scaling is ever needed.
Which should you pick?
Whichever is in your printer. If you are in the United States or Canada, that is almost certainly Letter — the generator's default. Most of the rest of the world loads A4. If the calendar will be shared across the Atlantic, generate both: it is two clicks, and each audience gets a file that prints without compromise.
Paper weight, briefly
Ordinary office paper is 75–90 gsm (20–24 lb) and fine for a desk calendar. For a wall calendar that will be written on, 120 gsm (about 32 lb) stops the grid showing through and takes ink without cockling. Anything heavier is a poster, and most home printers start to complain.