Milimetre
| Millimetre | |
|---|---|
Ruler with millimetre and centimetre marks
|
|
| Unit information | |
| Unit system | SI derived unit |
| Unit of | Length |
| Symbol | mm or ㎜ |
| Named after | The metric prefix mille (Latin for "one thousand") and the metre |
| Unit conversions | |
| 1 mm in ... | ... is equal to ... |
| micrometres | 1×103 µm = 1000 μm |
| centimetres | 1×10−1 cm = 0.1 cm |
| metres | 1×10−3 m = 0.001 m |
| kilometres | 1×10−6 km |
| inches | 0.039370 in |
| feet | 0.0032808 ft |
The millimetre (International spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length. Therefore there are thousand millimetres in a metre. There are ten millimetres in a centimetre.
One millimetre is equal to 1000 micrometres or 1000000 nanometres. A millimetre is equal to exactly 5⁄127 (approximately 0.039370) of an inch.
Since 1983, the metre has been defined as "the length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second". A millimetre, 1/1000 of a metre, is therefore the distance travelled by light in 1/299792458000 of a second.
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Wikipedia