A3 Paper Size
The A3 paper size is 11.69 x 16.54”or 297 x 420 millimeters. 
It is not one of the standard paper sizes used in the US. However, it is widely used in most other countries around the world.
Other Information about A3 Paper
The word A3 refers to a specific type of paper. The A3 is one of the ISO paper sizes and as such is a world standard. The ISO (International Organization for Standardization) is responsible for the A3 and the other A series of papers.
The smallest is A10 and the biggest is A0. Due to the A3 paper size, folding the paper in half by the shortest side is equivalent to the next smaller A page size. If you fold the A3 paper in half by the short side, the dimensions will be equal to an A4.
The closest equivalent of the A3 in the American paper size is the ledger. It measures 279 x 432 millimeters or 11 x 17 inches.
History of the A Format System
The idea of ISO paper standards first emerged in 1922. A German engineer named Walter Porstmann suggested that standard paper sizes be established. By 1975, the ISO officially adopted the A and B formats as the standard paper sizes.
The A format system where A3 belongs is based on area. The biggest is A0 which is 1 sq meter. A1 is half of A0 and so on. It should also be stressed that all ISO sizes are ratios of the square root of 2. Just imagine the width as the square’s side. Also think of the height as the diagonal measurement of the square.
Comparisons of the Paper Sizes
The A4 paper measures 8.27 inches by 11.69 inches. It is compared to the American ledger size, but it is a bit longer. The A5 paper size is 5.83 inches by 8.27 inches.
Adoption of ISO Paper Sizes
The A format is now the standard used throughout the world. The notable exceptions are the United States and Canada where the 8.5 x 11 inch paper size is still preferred. However, both types of paper can be purchased easily. Majority of today’s printers and programs have support for these paper sizes.
If you are going to use the A3 paper size on your computer you have to change the options on the printer. You can access this feature by pressing ctrl + P.
