In the ISO paper size system, all pages have a height-to-width ratio of the square root of two (1:1.4142).
This aspect ratio is especially convenient for paper size. If you put two pages with this aspect ratio next to each other or equivalently cut one parallel to its shorter side into two equal pieces, then the resulting page will again have the same width/height ratio.
The ISO paper size concept
The ISO paper sizes are based on the metric system. The square-root-of-two ratio does not allow the height and width of the pages to be nicely rounded metric lengths. Therefore, the area of the pages has been defined to have nice metric values. As paper is usually specified in g/m², this allows easy calculation of the mass of a document if the format and number of pages are known.
Sheet size A0 has an area of 1 m².The ratio of the sides of A and B series papers is 1:2.
A SERIES - FOR ALL PRINTING WORK
| SHEET SIZE | MILLIMETRES |
|---|---|
| 4A0 | 1682 x 2378 |
| 2A0 | 1189 x 1682 |
| A0 | 841 x 1189 |
| A1 | 594 x 841 |
| A2 | 420 x 594 |
| A3 | 297 x 420 |
| A4 | 210 x 297 |
| A5 | 148 x 210 |
| A6 | 105 x 148 |
| A7 | 74 x 105 |
| A8 | 52 x 74 |
| A9 | 37 x 52 |
| A10 | 26 x 37 |
B SERIES - FOR POSTERS, WALL CHARTS, ETC
| SHEET SIZE | MILLIMETRES |
|---|---|
| B0 | 1000 x 1414 |
| B1 | 707 x 1000 |
| B2 | 500 x 707 |
| B3 | 353 x 500 |
| B4 | 250 x 353 |
| B5 | 176 x 250 |
| B6 | 125 x 176 |
| B7 | 88 x 125 |
| B8 | 62 x 88 |
| B9 | 44 x 62 |
| B10 | 31 x 44 |
C SERIES - FOR ENVELOPES OR FOLDERS TO TAKE A SERIES ITEMS
| SHEET SIZE | MILLIMETRES |
|---|---|
| C0 | 917 x 1297 |
| C1 | 648 x 917 |
| C2 | 458 x 648 |
| C3 | 324 x 458 |
| C4 | 229 x 324 |
| C5 | 162 x 229 |
| C6 | 114 x 162 |
| C7 | 81 x 114 |
| C8 | 57 x 81 |
| C9 | 40 x 57 |
| C10 | 28 x 40 |
STOCK SIZES - FOR NORMAL TRIMS
| SHEET SIZE | MILLIMETRES |
|---|---|
| RA0 | 860 x 1220 |
| RA1 | 610 x 860 |
| RA2 | 430 x 610 |
| RA3 | 305 x 430 |
| RA4 | 215 x 305 |
STOCK SIZES - FOR BLEEDS OR EXTRA TRIMS
| SHEET SIZE | MILLIMETRES |
|---|---|
| SRA0 | 900 x 1280 |
| SRA1 | 640 x 900 |
| SRA2 | 450 x 640 |
| SRA3 | 320 x 450 |
| SRA4 | 225 x 320 |