no A3 paper refers to the international general standard A3 paper, with a size of 297mm × 420mm； The positive dimension of 8 paper opening is 260 × 370mm, size 420 × 285mm。 The sizes of the two are different, but in the printing industry, 8-folio paper is usually A3 paper.
Generally, a piece of flat base paper cut according to national standards is called full open paper. On the premise of not wasting paper and facilitating printing and binding production operations, cutting the full opening paper into several small sheets with equal area is called how many openings. 8 open is to cut a full open paper into 8 pieces of paper with equal area.
Because there are several different series of paper formats in international countries, although they are all cut into the same number, their specifications are different. This is the reason why 8 open paper is different from A3 paper.
A3 refers to international standard paper (297) × 420), its paper size is unique, and the commonly said 8-folio paper refers to the 8-folio paper of group A in China's 1965 national standard (273) × 393）。