12mm

12 millimeters (12 mm) is a unit of length in the metric system. It equals 0.012 meters or 1.2 centimeters. In decimal inches, 12 mm is approximately 0.47244 inches, about 0.47 inches, which is close to half an inch but slightly smaller.

In everyday and technical contexts, 12 mm is a common nominal size for various components. In mechanical engineering and manufacturing, 12 mm frequently appears as a diameter for shafts, holes, or fasteners. The standard metric thread size M12 designates bolts and nuts with a nominal diameter near 12 mm; exact thread pitch varies by standard (for example, coarse and fine pitches exist within the M12 family). Measurements labeled as 12 mm can also refer to thickness, width, or spacing in parts and assemblies.

In photography and optics, a 12 mm focal length lens denotes a wide-angle lens on many camera formats. On full-frame cameras it provides a broad field of view, while on smaller sensors the effective field of view is influenced by the sensor’s crop factor, making the lens behave like a longer focal length in terms of angle of view.

Other uses include general sizing for components, tools, and fittings where a 12 mm dimension is specified for compatibility. The term is widely understood within metric measurement practices and is one of the common small-diameter references in engineering and design.