80mm

80 mm is a metric unit of length equal to 0.08 m or 8 centimetres and is commonly used in a variety of technical contexts. The conversion to the imperial system is approximately 3.15 inches. In firearms and artillery, the 80 mm designation most often refers to the bore diameter of a gun or mortar. Historical examples include the French 80 mm siege gun used during the 19th century, the German 8.8 cm Flak 18/36/37 (which has a bore of 88 mm but is sometimes approximated to 80 mm for comparison), and the modern 80 mm mortar trunnions employed by many armies for infantry support. Mortars of this calibre typically fire shells ranging from 2 to 5 kg and provide a balance between portability and firepower.

In civilian applications, 80 mm specifications appear in civil engineering as a gauge for pipe diameters, sheet metal scrolls, and automotive suspension components. The measurement is used as a standard size for various types of rubber gaskets, and for certain lenses in mini lens systems. Because 80 mm is a convenient round diameter, it is frequently referenced in standardisation documents such as ISO 21345 for measuring the thickness of painted surfaces or in DIN 5458 for precision mechanical parts. The consistency of the source material and its progression from historical to contemporary uses makes 80 mm an example of a measurement that remains relevant across disciplines.