Fig. 1. Dimension of AA paper sizes with respect to each other.
The ISO A Series paper size is widely used all over the world today. We know them as paper sizes like A4 and A3 which are common and the larger sizes A2, A1 and A0. It is base on the International Standards Organization ISO 216
ISO 216 defines the A series of paper sizes based on these simple principles:

- The height divided by the width of all formats is the square root of two (1.4142).
- Format A0 has an area of one square meter.
- Format A3 is A2 cut into two equal pieces. In other words, the height of A3 is the width of A2 and the width of A3 is half the height of A2.
- All smaller A series formats are defined in the same way. If you cut format An parallel to its shorter side into two equal pieces of paper, these will have format A(n+1).

The standardized height and width of the paper formats is a rounded number of millimeters.

HOW TO FOLD AN A3 MAP INTO AN A4 REPORT SIZE MAP
Fig. 2. Example of an A3 map with suggested dimensions.
Dimensions above be converted into the next bigger paper size (A2) by multiplying the value by the square root of 2 (1.4142). Ex. The right margin of 1.25 cm in A3 will be 1.76 cm in A2 (1.25 cm X 1.4142).
Step 1. Fold the paper map (A3) into two (2) equal halves as shown in Fig. 3.
Fig. 3
Step 2. Fold the other half, containing the North Arrow, Scale, Legend, etc. in two (2) equal halves, as shown in Fig. 4.
Fig. 4
Fig. 5. A folded version of an A3 size paper map into an A4 report size map.

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