The common letter-sized paper used in Europe and in most locations outside of North America. At 8.3 x 11.7" (210x297mm), A4 paper is slightly narrower and a little longer than "A" size 8.5 x 11 ...

Paper is available in many sizes, with A0 being the largest and the most common size being A4. Each is half the area of the one before, ie A4 paper (297 mm × 210 mm) is half the size of A3 paper ...