What international standard paper size (denoted by the letter A plus a number) has the dimensions of 297 x 420mm?
Paper size containing less than 10 micrometers of paper The international paper size standard is ISO 216. It is based on the German DIN 476 standard for paper sizes. ISO paper sizes are all based on a single aspect ratio of the square root of 2, or approximately 1:1.4142. There are different series, as well as several extensions. The following international paper sizes are included in Cascading Style Sheets (CSS): "A3", "A4", "A5", "B4", "B5". The base A0 size of paper is defined as having an area of 1 m and a dimension ratio of 1 to , making the A0 paper
Letter (paper size) g/m. The most common density of A4 paper is 80 g/m. The precise origins of the dimensions of US letter-size paper (8.5 × 11 in) are not known. The American Forest & Paper Association says that the standard US dimensions have their origin in the days of manual paper making, the 11" length of the standard paper being about a quarter of "the average maximum stretch of an experienced vatman's arms". The letter size falls within the range of the historical quarto size, which since pre-modern times refers to page sizes of wide and high, and it is indeed almost