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.
- Film format, with which film gauge is sometimes confused. While film gauge comprises part of a film format's definition, a film format also includes the standards for image capture and projection.
- One hundred years of film sizes
- Running time calculator according to gauge, length and frame rate of the film