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 ...

However, this ISO 216 sized paper has one important feature. That is, ``If you fold or cut it in half, it will be one size smaller with the same aspect ratio.'' If you fold A4 size paper in half ...