A3 is a standard size of paper. One sheet is 297 millimetres by 420 millimetres — about the size of two A4 sheets placed side by side. Schools, offices, and print shops in Europe, Japan, and Taiwan use it for posters, big tables, music, and drawings that need more room than a normal printer page. It belongs to the international A-series of paper sizes (ISO 216). In that system each next size is half the one before, cut parallel to the shorter side, so A3 is twice A4, and A2 is twice A3. In the United States people more often use sizes called letter and tabloid, so A3 is less common there. When someone says “print it on A3,” they mean this large standard sheet, not a special kind of paper.