7 mm may refer to:

Rail transport modelling

7 mm scale 7 mm scale, also known as British 0 scale is a model railway scale of 1:43.5 (or 7 mm to 1 ft; hence its name). The scale is thus different from O scale, American 0 scale (1:48) and O scale, European 0 scale (1:45) For standard ga ...

, 1:43.5 scale with rails apart, representing standard gauge * HOn2 gauge, 1:87.1 scale with rails apart, representing narrow gauge

Firearms

7 mm caliber This is a list of firearm cartridges which have bullets in the caliber range. *''Length'' refers to the cartridge case Case or CASE may refer to: Containers * Case (goods), a package of related merchandise * Cartridge case or casing, a fir ...

, bullet cartridges used in guns {{Letter-Number Combination Disambiguation