Micro-
prefix for measurement unit symbols, denoting a multiple of 10 to the −6th power
Micro (Greek letter μ, mu, non-italic) is a unit prefix in the metric system denoting a factor of one millionth (10−6). It comes from the Greek word μικρός (mikrós), meaning "small".
It is the only SI prefix which uses a character not from the Latin alphabet. In Unicode, the symbol is represented by U+03BC μ GREEK SMALL LETTER MU or the legacy symbol U+00B5 µ MICRO SIGN. The prefix "mc" is also commonly used; for example, "mcg" denotes a microgram (whereas mg denotes a milligram).
Examples
Typical bacteria are 1 to 10 μm in diameter.
Human hair typically varies in diameter from 17 to 181 μm.
Eukaryotic cells are typically 10 to 100 μm in diameter.
Capacitance values of electrolytic capacitors in everyday electronics typically range from 1 to 47,000 μF
Symbol encoding in character sets
The official symbol for the SI prefix micro is a Greek lowercase mu (μ). For reasons stemming from its design, Unicode has two different character codes for the letter, with slightly different appearance in some computer fonts, although most fonts use the same glyph. U+03BC μ GREEK SMALL LETTER MU is in the Greek range.
This brief starts where responsible research should: with the source description of “Micro-” as prefix for measurement unit symbols, denoting a multiple of 10 to the −6th power. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as prefix for measurement unit symbols, denoting a multiple of 10 to the −6th power. Its deeper value depends on whether names, dates, institutions and citations support that framing.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 19, 2026. The linked authority identifier is Q154121. None of the 0 selected statements returned an explicit reference.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Micro-” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.