Architectural Paper Sizes ANSI
Architectural Paper Sizes
North America also has a special series of paper sizes defined for architectural purposes, in general these have aspect ratios of 4:3 or 3:2. These aspect ratios are very similar to the aspect ratio used for computer screens.
The following table gives details of the sizes for architectural paper.
| Size | Width x Height (mm) | Width x Height (in) | Aspect Ratio |
| Arch A | 229 x 305 mm | 9.0 x 12.0 in | 4:3 |
| Arch B | 305 x 457 mm | 12.0 x 18.0 in | 3:2 |
| Arch C | 457 x 610 mm | 18.0 x 24.0 in | 4:3 |
| Arch D | 610 x 914 mm | 24.0 x 36.0 in | 3:2 |
| Arch E | 914 x 1219 mm | 36.0 x 48.0 in | 4:3 |
| Arch E1 | 762 x 1067 mm | 30.0 x 42.0 in | 7:5 |
ANSI Standard Paper Sizes
ANSI (American National Standards Insitute) defined a regular series of paper sizes based around the Letter (8.5" x 11") format, with this becoming the A sizes and larger sizes being B, C, D & E. Surprisingly these ANSI standard sizes were defined in 1995 well after the ISO standard sizes.
Unlike the ISO standard sizes which have the single aspect ratio of 1: root2, ANSI standard sizes have two aspect ratios 1:1.2941 and 1:1.5455 which means that enlarging and reducing between the sizes is not as easy as with the ISO sizes and leaves wider margins on the enlarged/reduced document.
| Size | Width x Height (mm) | Width x Height (in) | Aspect Ratio | Nearest ISO |
| A | 216 x 279 mm | 8.5 x 11.0 in | 1:1.2941 | A4 |
| B | 279 x 432 mm | 11.0 x 17.0 in | 1:1.5455 | A3 |
| C | 432 x 559 mm | 17.0 x 22.0 in | 1:1.2941 | A2 |
| D | 559 x 864 mm | 22.0 x 34.0 in | 1:1.5455 | A1 |
| E | 864 x 1118 mm | 34.0 x 44.0 in | 1:1.2941 | A0 |