Themillimetre (SI symbol:mm; international spelling) ormillimeter (American spelling) is a unit oflength in theInternational System of Units (SI), equal to one thousandth of ametre, the SI base unit of length.
The term "mil" is sometimes used colloquially for millimetre. However, in the United States, "mil" traditionally means athousandth of an inch, which may cause confusion.
On a standard metric ruler, the smallest divisions are typically millimetres.[3]
Precision engineering rulers may show increments of 0.5 mm.
Digital calipers often measure to 0.01 mm accuracy.[4]
Examples:- Microwaves with a frequency of 300 GHz have a wavelength of 1 mm.- Using frequencies from 30–300 GHz for millimetre-wave communications allows high-speed data transfer (e.g., 10 Gbps).[5]- The smallest visible object to the human eye is around 0.02–0.04 mm (e.g., a thin human hair).[6]- A typical sheet of paper is between 0.07 mm and 0.18 mm thick; copy paper is about 0.1 mm.[7]
