The DIN A series (ISO 216:1975) includes the following formats:
DIN A0 | 841 x 1189 mm | Quadruple sheet | |
DIN A1 | 594 x 841 mm | Double sheet | |
DIN A2 | 420 x 594 mm | Sheet | |
DIN A3 | 297 x 420 mm | Half sheet | |
DIN A4 | 210 x 297 mm | Quarter sheet (note paper) | |
DIN A5 | 148 x 210 mm | Eighth sheet (page) | |
DIN A6 | 105 x 148 mm | Half page | |
DIN A7 | 74 x 105 mm | Quarter page (postcard) | |
DIN A8 | 52 x 74 mm | Eighth page | |
DIN A9 | 37 x 52 mm |
The width-to-height-ratio (aspect ratio) is √2 : 1. It starts with the DIN A0 paper size, which measures 841 x 1189 mm.
From the base format of this DIN standard, the next smaller sizes are calculated with the formula width : height = √2 : 1