International Paper Sizes, Formats & Standards ExplainedISO Paper Sizes Standard Overview & Rationale The ISO paper size A standard is based on each size being half of the size of the previous one, when folded parallel to the shorter lengths. This system allows for a variety of useful applications, such as the enlarging and reducing of images without any cutoff or margins, or folding to make a booklet of the next size down. The mathematics behind this
