Film gauge is a physical property of
photographic or
motion picture film stock which defines its width. Traditionally the major film gauges in usage are
8 mm,
16 mm,
35 mm, and
65/70 mm (in this case 65 mm for the negative and 70 mm for the release print; the extra five millimeters are reserved for the magnetic soundtrack). There have been other historic gauges in the past, especially in the silent era, most notably
9.5 mm film, as well as a panoply of others ranging from 3 mm to 75 mm.