The square inch equals 6.4516 square centimetres exactly. Used in US engineering, tile specifications, stamp areas and pressure conversion (PSI = pounds per square inch). A US letter-size sheet is 93.5 in².
Real-world: A US letter page is 93.5 in². A common US tile is 144 in² (1 ft²). Credit card ≈ 7.1 in².
Read full square inch reference →The metric dunam equals 1000 square metres exactly. It is the standard land unit in Israel, Palestine, Turkey and parts of the former Ottoman Empire. Other regional "dunams" have existed historically, but the metric dunam (1000 m²) is the modern standard.
Real-world: An Israeli small farm might be 50 dunams (5 ha). Agricultural yields sometimes quoted per dunam.
Read full dunam reference →