Size Unit Area 4A0   2A0   A0   A1   A2   A3   A4   A5   A6   A7   A8   A9   A10 in sq mm   sq cm   sq m   sq in   sq ft   sq yd is 0.06237

# Areas Of A Series Paper Sizes

The area of each of the A paper sizes are set by the A paper size definitions (see below). A0 is defined as having an area of 1 square metre, however the A paper size standard also specifies that each size is rounded to the nearest millimetre. Thus A0 is 841mm x 1189mm giving an area of 0.999949 square metres.

Theoretically the area of a sheet of paper of size An can be calculated as 1/2n m2.

The following table gives theoretical areas compared with actual areas for each of the A paper sizes from 4A0 to A10.

## Table of Theoretical and Actual Areas of A Paper Sizes

SizeTheoretical Area (sq m)Actual Area (sq m)Difference (sq m)Difference (%)
4A043.9997960.0002040.0051%
2A021.9998980.0001020.0051%
A010.9999490.0000510.0051%
A10.50.4995540.0004460.0892%
A20.250.249480.000520.208%
A30.1250.124740.000260.208%
A40.06250.062370.000130.208%
A50.031250.031080.000170.544%
A60.0156250.015540.0000850.544%
A70.00781250.007770.00004250.544%
A80.003906250.0038480.000058251.4912%
A90.0019531250.0019240.0000291251.4912%
A100.00097656250.0009620.00001456251.4912%

At the smaller sizes (A8, A9 & A10) the discrepancy between the theoretical area of the sheet and the actual area is about 1.5%. Larger sizes have significantly lower differences between the theoretical area and the actual area.

## A Series Paper Sizes Defined

The A series paper sizes are defined in ISO 216 by the following requirements:

• The length divided by the width is 1.4142
• The A0 size has an area of 1 square metre.
• Each subsequent size A(n) is defined as A(n-1) cut in half parallel to its shorter sides.
• The standard length and width of each size is rounded to the nearest millimetre.

Note: For reference the last item is there because the root 2 aspect ratio doesn't always give a whole number.