Is A4 paper is bigger than A5 paper?

No, A4 paper is not bigger than A5 paper. A4 paper is actually smaller than A5 paper. The sizes of A4 and A5 paper are defined by the ISO 216 standard, which is an international standard for paper sizes. A4 paper has dimensions of 210 × 297 millimeters (8.3 × 11.7 inches), while A5 paper has dimensions of 148 × 210 millimeters (5.8 × 8.3 inches). Therefore, A5 paper is larger than A4 paper.