The first time the ratio of length to width was written in a letter dated 25 October 1786. This letter was from the German Georg Christoph Lichtenberg to Johann Beckmann. He wrote here about the advantages of basing paper on a √2 ratio. Lichtenberg is known for the ratio between length and width of a surface which remains the same after the narrated halving of the surface. The result is 1:√2.

He proposed the standardized paper size system used globally today except in Canada and the US defined by ISO 216, which has A4 as the most commonly used size.