the standard size of typing paper everywhere except the United States, 210 × 297 mm, about 8 ¼ × 11 ¾ inches. American typing paper is 8 ½ × 11 inches.

A4 is part of an ISO standard for paper sizes (chosen so that A0 paper [840 × 1189 mm] has an area of 1 square meter and each size can be cut in half to make the next smaller one. Thus, the area of a sheet of A4 paper is 1/16 m ² ). For table, see paper sizes (ISO) .