Paper sizes: all dimensions
How big is an A4 sheet? And an A3? All paper size dimensions in mm, cm, inches and pixels, with a visual comparison.
Visual comparison (A series)
How the A series works
The ISO 216 standard starts from A0 (841 × 1189 mm, exactly one square meter): each next size is made by halving the long side. That's why two A5 sheets side by side make an A4, two A4 make an A3, and so on. The side ratio is always √2.
What the pixels are for
If you're preparing a file for print, multiply inches by DPI: an A4 at 300 DPI (print quality) is 2480 × 3508 pixels. At 72 DPI you get «screen» dimensions instead.