Paper Size -Basic Knowledge About Dimensions

ISO A paper

The A paper size system was officially adopted in Europe in the 19^th century and has since spread worldwide. Currently, except for the United States and Canada, almost all countries use the A paper size. A4 is the most commonly used standards business letter size in English-speaking countries.

The size of A series of papers is defined by the ISO 216 standard and is logical. The largest size, A0, is 1 square meter. The aspect ratio (length to width) remains constant for all sizes (1:1.41). In simple terms, folding the A0 paper along its short side results in the A1 size. Folding the A1 size again gives the A2 size, and so on.

ISO B paper

The B series of paper sizes are defined by the ISO 216 in the international size standard. The B series of paper is less common than A series. The aspect ratio of the B series paper is 1:√2, the area of the B series paper is the geometric mean of the A series paper. For example, the size of B1 lies between A0 and A1.

ISO C paper

The C series paper sizes are defined by the ISO 269 paper size standard. The C series is most commonly used for envelopes. The aspect ratio of the C series envelopes is 1:√2, which means that if an A4 sheet of paper is folded in half so that its shorter side is parallel, it can fit perfectly into a C5 envelope.