| 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 micrometre (Commonwealth English as used by the International Bureau of Weights and Measures;[1] SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron,[2] is a unit of length in the International System of Units (SI) equalling 1×10−6 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).[1]
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 (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,[1] and for grading wool by the diameter of the fibres.[3] The width of a single human hair ranges from approximately 20 to 200 μm.
- ^ a b c "micrometre". Encyclopædia Britannica Online. Retrieved 18 May 2014.
- ^ "Writing with SI (Metric System) Units". NIST. 13 January 2010.
- ^ "Wool Fibre". NSW Department of Education and Communities. Archived from the original (Word Document download) on 17 June 2016. Retrieved 18 May 2014.