Mini zine on A4 vs US Letter: sizes, differences and which to pick

An 8-page one-sheet zine divides the sheet into four columns and two rows, so each page is one quarter of the long edge by one half of the short edge. A4 is 210 by 297 mm, so a panel is 74.25 by 105 mm, which is exactly A7. US Letter is 8.5 by 11 inches, so a panel is 2.75 by 4.25 inches, or 69.85 by 107.95 mm: slightly narrower and slightly taller than the A4 panel.

Print the same layout on the bigger sheets and every page doubles in area. A3 gives A6 panels of 105 by 148.5 mm; Tabloid (11 by 17 inches) gives 4.25 by 5.5 inch panels. Those sizes are large enough for a photo zine that reads like a small book, and the fold is identical.

A4 has a ratio of 1 to the square root of 2, about 1.414; Letter is 1.294. That difference changes the shape of every panel. Print an A4 zine file on Letter paper at actual size and the layout is 17 mm too tall and the folds miss; scale it to fit and the panels shrink and the centre shifts. Either way the slit lands in the wrong place. Zine guides written for US readers give measurements in inches for Letter, and European ones assume A4, which is why instructions from different sources never quite agree.

The same applies to the stapled booklet and the accordion. Foldpic lays every product out from the paper you choose, so an A4 project produces an A4-shaped PDF and a Letter project a Letter one, and the templates re-flow to the panel proportions rather than being stretched.

Choose the paper your printer already has. In the US, Canada and a few other countries that is Letter; almost everywhere else it is A4. Foldpic defaults from your locale and lets you change it at any time before export. If you are sending a zine to friends in another country, make a version for each paper so nobody has to scale it, or send the folded zine itself, which does not care.

Go up to A3 or Tabloid when photos are the point. The A6 panels of an A3 zine are big enough for a single photo per page to read well, and many photo inkjets take A3. A copy shop will print A3 or Tabloid for you if your home printer will not.

If you share files with people on the other paper system, keep the project in Foldpic and export twice, once per paper, rather than converting the PDF. The layouts re-flow to the panel proportions, so a caption that fits under an A4 panel also fits under the slightly narrower Letter one, and the fold marks are recomputed for each sheet. Label the two files clearly, because an A4 PDF printed on Letter at actual size loses 17 mm at one end and the slit lands in the wrong place.

The finished zines are close enough in size that they sit together on a shelf, and nobody reading them will notice the difference. It is only the printing step where the two sheets refuse to mix.