paper sizes

1.American National Standards Institute (ANSI) sizes. Also called North American sheet sizes, they are used mainly in the US, Canada, and some Caribbean countries, and are referred-to by their dimensions: (1) 25 x 38 inch (2) 23 x 35 in., (3) 19 x 25 in., (4) 17.5 x 22.5 in., (5) 11 x 17 in., (6) 8.5 x 14 in., also called legal size paper, (7) 8.5 x 11 in., also called A-size paper or letter size paper.

2.International (ISO) paper sizes: Used in most of the world, these sizes are based either on A0 sheet (area 1 square meter) or B0 sheet (area 1.414 square meter). Each smaller size is obtained by cutting the previous size in half such that the narrowside-to-wideside (width-to-height) ratio remains the same (1:v2). A-series: A0 (841 x 1189 millimeter or 33.11 x 46.81 inch), A1 (594 x 841 mm or 23.40 x 33.11 in.), A2 (420 x 594 mm or 16.55 x 23.40 in.), A3 (297 x 420 mm or 11.70 x 16.55 in.), A4 (210 x 297 mm or 8.27 x 11.70 in.), A5 (148 x 210 mm or 5.85 x 8.27 in.), A6 (105 x 148 mm or 4.13 x 5.85 in.), A7 (74 x 105 mm or 2.92 x 4.13 in.), A8 (52 x 74 mm or 2.06 x 2.92 in.), A9 (37 x 52 mm or 1.46 x 2.06 in.), A10 (26 x 37 mm or 1.03 x 1.46 in.).