A4 and Letter Are Not the Same Size and It Breaks Everything

The A4 vs Letter paper size difference causes more document formatting problems than any other single issue in international business. A4 is taller and narrower. Letter is shorter and wider. A document formatted for one will not print correctly on the other. The sizes A4: 210 x 297 mm (8.27 x 11.69 inches) Letter: 215.9 x 279.4 mm (8.5 x 11 inches) Legal: 215.9 x 355.6 mm (8.5 x 14 inches) A4 is used by every country except the US, Canada, and a few others that use Letter. This means most of the world's documents are formatted for A4. The A-series design The A-series paper sizes follow an elegant mathematical principle: each size is the previous size cut in half. A1 is A0 cut in half. A2 is A1 cut in half. And so on. The aspect ratio is constant: 1:sqrt(2) (approximately 1:1.414). This means cutting an A4 sheet in half produces two A5 sheets with the same proportions. No other aspect ratio has this property. A0: 841 x 1189 mm (1 square meter area) A1: 594 x 841 mm A2: 420 x 594 mm A3: