A3 is a paper size that people in the international community embrace for drawings, art posters, and diagrams. This size is also frequently used in laser printers to output two A4 pages as a spread.

A3 Dimensions

A3 measures 297 × 420 millimeters or 11.69 × 16.54 inches. In PostScript, we round off the dimensions to 842 × 1190 points.

In the American market, customers rarely use ISO paper sizes. The US-alternative to A3 is called tabloid or ledger (ANSI B) and measures 11 x 17″ or 279 × 432 mm.

This chart shows how A3 compares to the other international print sizes:

Table of Paper Sizes 4A0 to A10

SizeWidth x Height (mm)Width x Height (in)
4A01682 x 2378 mm66.2 x 93.6 in
2A01189 x 1682 mm46.8 x 66.2 in
A0841 x 1189 mm33.1 x 46.8 in
A1594 x 841 mm23.4 x 33.1 in
A2420 x 594 mm16.5 x 23.4 in
A3297 x 420 mm11.7 x 16.5 in
A4210 x 297 mm8.3 x 11.7 in
A5148 x 210 mm5.8 x 8.3 in
A6105 x 148 mm4.1 x 5.8 in
A774 x 105 mm2.9 x 4.1 in
A852 x 74 mm2.0 x 2.9 in
A937 x 52 mm1.5 x 2.0 in
A1026 x 37 mm1.0 x 1.5 in

A3 is part of the ISO 216 standard.

A3 is part of a series of page sizes, called the ISO A or ISO 216 standard. Experts base this international standard on the German DIN 476 standard from 1922. Our industry often refers to A3 to DIN A3. The Japanese market adopted the same spectrum of paper sizes as the JIS P 0138-61 standard.

By folding an A3 in half along the shortest side, we create a DIN a4 document. Two A3 pages together as a spread equal the A2 paper size. We produce paper sizes A0 (a surface of one square meter) to A10. The height/width ratio remains constant for all sizes: 1:1.41 or the square root of 2. The dimensions always get rounded to the nearest millimeter.


What resolution do you need to print an A3 size picture?

To output an image correctly, the art file needs to be a minimum resolution. This number of pixels depends on the required output quality.

At 300 PPI (pixels-per-inch) the image needs to be 3508 x 4961 pixels. This ratio is the required resolution for quality offset printing. Customers can view the art clearly from a short distance (such as books, posters, magazines). 

A phone or digital camera with decent image quality and a resolution of 12 megapixels or more is needed to print high-quality A3 size pictures. Since people generally view pictures this size from a somewhat longer distance, an 8-megapixels camera will still offer excellent quality.

How to Print A3

You could order 12×18 print, and ask us to cut it down to 11.7 x 16.5 in.

Or you can select the US alternative – 11×17.

Other sources of information

An elaborate yet easy to read article on the ISO 216 standard can be found here.