Dimensions of the A series paper sizes 4A0, 2A0, A0, A1, A2, A3, A4, A5, A6, A7, A8, A9 and A10 in both inches and mm, cm measurements can be obtained. To many people wordwide, excluding North America and Canada, the most familiar paper size size is A4 (a familiar 210mm x 297mm). An A4 piece of paper measures 210 × 297 mm or 8. A4 measures 210 × 297 millimeters or 8. The ISO 216 standard, which includes the commonly used A4 size, is the international standard for paper size.