The paper size is formed by sheet length to his height, these dimensions are described by the international standard ISO 216 and in North American sizes too.

The base format for paper, in the international standard, is a sheet of 1 m² (A0). Subsequent formats (A1, A2, A3 etc.) are obtained by cutting in half the paper on the longest side.

The ISO formats have a ratio given by √2 that creates correlations between formats. For example, if a sheet is divided into two equal halves parallel to its shorter side, then also the two halves will have a ratio of √2.

There is a scalability between format and the other, ie the lower formats can be obtained from those of greater extent eg. you can get an A4 sheet from the A3, an A3 sheet by an A2 and so on.

The weight of a sheet is measured in grams this allows us an easy calculation of the weight by counting the number of sheets: a standard A4 sheet of 80 g / m² weights 5 grams.

In addition to the A series, B series exists for special uses (passports, envelopes and posters). The area of ​​the B series is the geometric mean of the corresponding sheet format A: B1 is between A0 and A1, its area is 0.71 m² (√0.5). The B0 will be 1 meter long and the other sizes of the B series are half, fourth and other fractions of a meter. The B5 is often used for books.

Finally, there is a set C defined by ISO 269. The area of ​​C series sheets is the number of sheets A and B; therefore, the area of ​​a C4 sheet is the geometric mean of an A4 and B4 a. It is clear that the C4 is a bit wider than the A4, and B4 slightly larger than the C4. This series is almost exclusively used for envelopes eg. a letter written on A4 may be inserted inside a C4 envelope, which can be inserted in a B4 envelope.

Below the summary list of daily most used formats in office, all paper sizes are in cm and mm

What is the measure of A1 paper?
The A1 format has dimensions 59.4 x 48.1 cm that is 597x481 mm.

What is the measure of A2?
The A2 has dimensions 42.0 x 59.4 cm that is 420x594 mm.

What is the measures of A3?
The A3 has dimensions 29.7 x 42.0 cm that is 297 x 420 mm.

What is the measure of A4?
The most frequently used paper size and known is the A4, A4 are 21x29,7 cm that is 210 × 297 mm.

What is the measure of A5?
The A5 is a rectangle 14.8 x 21 cm that is 148 × 210 mm.

What is the measure of A6?
The A6 paper size is 10,5x14,8 cm format or 105 × 148 mm and is often used for printing photos.

What is the measure of A0?
The A0 is an entire sheet of 84.1 x 118.9 cm.

These are the paper formats most used and their size.