Understanding A4 Paper Dimensions and the ISO 216 Standard

https://a4paperdimensionsdeck.silverstonebrief.com/posts/understanding-a4-paper-dimensions-and-the-iso-216-standard

A4 paper is 210 by 297 millimeters, part of ISO 216's elegant system where each size is half the previous one. This standard simplifies printing and copying globally, with A4 being the go-to for letters and documents. Its consistency makes scaling designs effortless; A3 is twice the size, A5 half.