There are three ranges of paper sizes, prefixed A, B, and C. The most widely used for general printing and letterhead stationery is the A series. The most common of these sheet sizes is the international letterhead size A4, which measures 8-1/4 x 11-3/4 in (210 x 297 mm). Other standard sizes include North American Letter 8.5 x 11 in (216 × 279 mm) and Legal 8.5 x 14 in (216 × 356 mm).
This is the international standard, with an aspect ratio of approximately 1:√2
| Paper Size | Inches | Millimeters | Centimeters |
|---|---|---|---|
| A0 | 33-1/8 x 46-13/16 in | 841 x 1188 mm | 84.1 x 118.8 cm |
| A1 | 23-3/8 x 33-1/8 in | 594 x 841 mm | 59.4 x 84.1 cm |
| A2 | 16-1/2 x 23-3/8 in | 420 x 594 mm | 42.0 x 59.4 cm |
| A3 | 11-3/4 x 16-1/2 in | 297 x 420 mm | 29.7 x 42.0 cm |
| A4 | 8-1/4 x 11-3/4 in | 210 x 297 mm | 21.0 x 29.7 cm |
| A5 | 5-7/8 x 8-1/4 in | 148 x 210 mm | 14.8 x 21.0 cm |
| A6 | 4-1/8 x 5-7/8 in | 105 x 148 mm | 10.5 x 14.8 cm |
| A7 | 2-15/16 x 4-1/8 in | 74 x 105 mm | 7.4 x 10.5 cm |
| A8 | 2-1/16 x 2-15/16 in | 52 x 74 mm | 5.2 x 7.4 cm |
| A9 | 1.5 x 2 in | 37 x 52 mm | 3.7 x 5.2 cm |
These sizes are common in the United States and Canada.
| Paper Size | Inches | Millimeters | Centimeters |
|---|---|---|---|
| Letter | 8.5×11 | 216×279 mm | 21.6 x 27.9 cm |
| Legal | 8.5×14 | 216×356 mm | 21.6 x 35.6 cm |
| Ledger (or Tabloid) | 11×17 | 279×432 mm | 27.9 x 43.2 cm |