#0excludeGlossary (1/1,000,000) of a meter.
The micrometre (or micrometer in US spelling; symbol: μm) is a unit of length in the International System of Units (SI) equalling 10−6 metre (SI standard prefix "micro-" = 10−6); that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.00004 inch). Also known as a micron.
| micrometre | |
|---|---|
 A 6 μm diameter carbon filament above a 50 μm diameter human hair | |
| General information | |
| Unit system | SI |
| Unit of | length |
| Symbol | μm |
| Conversions | |
| 1 μm in ... | ... is equal to ... |
| SI base units | 10−6 m |
| Natural units | 1.8897×104 a0 |
| imperial/US units | 3.9370×10−5 in |
The nearest smaller common SI unit is the nanometre, equivalent to one thousandth of a micrometre, one millionth of a millimetre or one billionth of a metre (10−9 or 0.000000001 m).
The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres. The width of a single human hair ranges from approximately 20 to 200 μm.
English
Pronunciation
- IPA(key): /ˈmaɪkɹɒn/
- Rhymes: -aɪkɹɒn
Etymology 1
From French micron, from Ancient Greek μικρόν (mikrón), neuter of μικρός (mikrós, “small”).
Noun
micron (plural microns)
- (physics, metrology) Synonym of micrometre (“one-millionth of a metre”)