B5

The B5 envelope has dimensions of 250mm x 176mm giving it a surface area of 44,000 mm2. The maximum enclosure size is typically around 170mm x 244mm. The B5 is part of the ISO 269 "B" series of paper sizes, nestled between B6 and B4. It shares the same 1.414 ratio of width to height as other ISO paper sizes. The B5 is close in size to the C5 envelope which measures 162mm x 229mm. The slightly shorter but wider B5 provides more space than C5 and can fit an A4 sheet folded twice. It offers a versatile mid-size between postcards and large shipping packages. B5 envelopes are commonly used for commercial mailings, catalogs, books, and magazines. Their origins trace back to the German DIN 476 paper standard which influenced ISO formats. The B5 remains widely used in Europe and Asia.