paperikokoihin

Paperikokoihin, or paper sizes, refer to standardized dimensions of sheets used for writing, printing, and packaging. The system most widely adopted internationally is the ISO A and B series, with supplementary sizes used in North America and elsewhere. ISO 216 defines the A-series, with A0 to A10. An A0 sheet has an area of 1 square metre; each subsequent size is half the area of the previous. Practical sizes include A4 (210 mm × 297 mm), A3 (297 × 420 mm), and A5 (148 × 210 mm). The series is designed so that folding an A(n) sheet in half yields A(n-1). B-series offers intermediate sizes such as B0, B1, B2, etc., used for posters, passports, and envelopes, following the same halving principle but with different dimensions for better approximate area sizes. North American sizes such as Letter (8.5 × 11 inches) and Legal (8.5 × 14 inches) are not part of ISO 216 but remain common in several markets; printers in Europe and Finland usually default to A-series for most applications. The historical development of the system dates to early 20th-century Germany, with the concept refined by Walter Porstmann and later standardized internationally as ISO 216 in 1975. In Finland, as in much of the EU, A4 is the dominant size for correspondence, forms, and standard office documents. Understanding paperikokoihin supports interoperability among printers, publishers, and archives, ensuring consistent printing, folding, and cutting practices. See also: ISO 216, paper size.