84mm

84 millimeters (84 mm) is a unit of length in the metric system equal to 0.084 meters. It is used to specify dimensions in engineering, manufacturing, and construction, and appears in product specifications, technical drawings, and packaging measurements.

In firearms and military equipment, 84 mm refers to a caliber size. The 84 mm calibre is associated with several anti-tank and anti-armor systems, the most well-known being the Carl Gustaf recoilless rifle, a man-portable weapon developed in Sweden. This system fires rounds in the 84 mm family, including high-explosive and anti-tank variants, and has seen widespread adoption since the mid-20th century.

In photography and optics, 84 mm denotes a focal length used on cameras with 35 mm sensors and equivalent focal lengths on crop sensors. An 84 mm lens is categorized as a short telephoto, commonly used for portraiture and scenarios where moderate compression and subject isolation are desirable. On full-frame cameras, it provides a tighter field of view than standard lenses and is valued for its balance between working distance and background blur.

Other uses of 84 mm include standardizing diameters and components across various industries, such as connector housings, mechanical parts, and packaging dimensions where metric sizing is prevalent.

Notes: The meaning of 84 mm depends on context and is not interchangeable across disciplines. It most often refers to either a physical length or a firearm caliber in military contexts.