Do you know why A4 paper is known as ‘A4’ ?

Paper Size

Today in Europe and Asia the popular paper sizes are ‘A’ series.The ratio of length and breadth(l/b=√2) in this series is √2. The ratio of √2 in paper size was first noted in 1786 by the German Scientist and Philosopher , George Christoph Lichtenberg.

There are 11 sizes of paper in ‘A’ series(A0 to A10).

A0=1 m2.(A0= 841 mm × 1,189 mm).

A1=1/2 of A0

A2=1/2 of A1

A3=1/2 of A2

A4=1/2 of A3=1/16 of A0=1/16 m2.
A4=210 mm×297mm

And many more…

Map of the world showing adoption of ISO A4 (blue) vs. US-Letter (red)

Did you know ??

The International Paper Sizes (like A3,A4 e.t.c.) are based on the square root of 2.

Photos taken from Wikipedia

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