ISO Paper Sizes

To find the dimensions for A, B, and C paper sheets of the ISO standard, read on!

What is ISO Paper anyway?

ISO (International Organisation for Standardisation) 216 paper sizes are based on an aspect ratio of approximately 1:1.4142 – the square root of 2. The base format (A0) is a sheet spanning 1m² in area. Successive sheets in the series are made by halving the preceding paper size along the larger edge.

The advantage of this system lies in scaling: if a sheet with an aspect ratio of √2 is divided into two equal halves parallel to its shortest sides, then the halves will again have an aspect ratio of √2.

Developed from earlier ideas in Germany in 1922, the system quickly spread to other countries, and was established as an ISO standard in 1975.

A Series

The most frequently used of this series is A4. The US ‘Letter’ paper size – that you may frequently select by mistake in MS Word (as I do) – is 6mm wider and 18mm shorter than this.

Sheet	Dimensions (mm)
A0	1189 x 841
A1	841 x 594
A2	594 x 420
A3	420 x 297
A4	297 x 210
A5	210 x 148
A6	148 x 105
A7	105 x 74
A8	74 x 52
A9	52 x 37
A10	37 x 26

B Series

In less common use, the B Series is the geometric mean of successive A sheets. B sizes are usually found in poster design, books and envelopes.

Sheet	Dimensions (mm)
B0	1414 x 1000
B1	1000 x 707
B2	707 x 500
B3	500 x 353
B4	353 x 250
B5	250 x 176
B6	176 x 125
B7	125 x 88
B8	88 x 62
B9	62 x 44
B10	44 x 31

C Series

The C series is used only for envelopes. The area of C series sheets is the geometric mean of the areas of the A and B series sheets of the same number.