F5

The F5 paper size format has compact dimensions of 165mm x 210mm for a total surface area of 0.0347 square meters. Falling between F4 and the PA5 size in the supplementary Asian F series, F5 mirrors the height of ISO A5 while gaining a bit of extra width. Sometimes referred to as metric quarto, F5 recalls the squat dimensions of historical quarto books while adapting the familiar A5 vertical space. This yields a versatile format well-suited for regional paperback books, catalogs, brochures and folders where the additional width eases cramped A5 layouts. As the F series aims to cater to local markets, F5 strikes a practical balance between height alignment with ISO for exportability and added width for regional preferences. The origins of F5 thus demonstrate strategic customization - maintaining A-based compatibility while tweaking horizontal space to yield upgrades over standardized sizes. So despite its simple role bridging F4 and PA5, F5 exemplifies adaptation through thoughtful dimensional adjustments resulting in a globally informed yet regionally optimized medium.