Unit of length 1/1000 of a metre
millimetre Ruler with millimetre and centimetre marks
General information Unit system SI Unit of Length Symbol mm Named after Frommetric prefix mille (Latin for "one thousand") and themetre Conversions 1 mmin ... ... is equal to ... micrometres 1000 centimetres 1 / 10 metres 1 / 1000 kilometres 1 / 1 000 000 decimetres 1 / 100 inches 0.039370 in feet 0.0032808 ft
Different lengths with respect to theelectromagnetic spectrum . Themicrowave spans from 1 metre to 1 millimetre. 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.
1 metre = 1000 millimetres 1 centimetre = 10 millimetres One millimetre is also equal to:
Since aninch is officially defined as exactly 25.4 millimetres, 1 millimetre is precisely5 ⁄127
Further information:
Metre Since 1983, themetre has been defined as "the length of the path travelled bylight invacuum during a time interval of1 / 299792458 of asecond ".[ 1]
A millimetre, being1 / 1000 of a metre, is the distance light travels in1 / 299 792 458 000 of a second.
Informal terminology [ edit ] 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.
To support layout compatibility with East Asian scripts (CJK), Unicode includes square symbols for:
Millimetre –U+339C ㎜ SQUARE MM Square millimetre –U+339F ㎟ SQUARE MM SQUARED Cubic millimetre –U+33A3 ㎣ SQUARE MM CUBED [ 2] These symbols are often used in Japanese typography to align unit symbols with text characters.
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] Look up
millimetre in Wiktionary, the free dictionary.
From smallest to largest (left to right). Commonly used units shown inbold italics
