100millimeter

100 millimeters, abbreviated 100 mm, is a unit of length in the metric system. It equals 0.1 meters and 10 centimeters, or about 3.94 inches.

Applications: It is commonly used to specify dimensions in engineering, manufacturing, construction, and design. Components are often sized with millimeter precision, for example a rod length of 100 mm or a hole diameter of 100 mm. It serves as a convenient reference dimension in layouts and tolerances.

Metric relationships: 1 meter equals 1000 millimeters, and 1 centimeter equals 10 millimeters, so 100 mm equals 10 cm and 0.1 m. In inches, 100 mm is approximately 3.94 inches.

Photography and optics: In camera work, a 100 mm focal length lens is common on 35 mm full-frame cameras, offering moderate telephoto magnification and portrait-friendly perspective. On smaller sensors, the effective focal length is multiplied by the crop factor, affecting field of view.

Terminology: The standard spelling is millimeter (American) or millimetre (British). The term "100 millimeter" is typically read as 100 millimeters; "100 millimeters" is standard in plural usage. The phrase is rarely used as a proper noun.