Micro Sign µ Copy and Paste

Tap µ to copy the SI prefix for one millionth: 5 µm, 250 µg, 10 µs. The table shows the keyboard route on every platform, and the notes explain why Unicode has two mu characters and which one to use.

µ

MICRO SIGN

U+00B5 · tap the symbol to copy

How to Type the Micro Sign

UnicodeU+00B5 MICRO SIGN
HTMLµ or µ
WindowsAlt + 0181 (numeric keypad); or type 00B5 then Alt + X in Word
MacOption + M
iPhoneNot under any long-press key; add a Text Replacement in Settings → General → Keyboard, or add the Greek keyboard and tap M for μ
AndroidGboard: no dedicated key; add a Greek layout and tap M, or set a shortcut in Gboard → Dictionary
LaTeX\micro (siunitx, gensymb) or \textmu (textcomp); \mu in maths mode

Micro Sign Variants and Lookalikes

Using the Micro Sign

The micro sign is the SI prefix for 10⁻⁶, one millionth. It goes in front of a unit symbol with no space: 0.5 µm for a bacterium, 400 µg of folic acid, 20 µs of latency, 47 µF on a capacitor. The prefix itself is spoken "micro", so 5 µL is "five microlitres". It is the only SI prefix that is not a Latin letter, which is exactly why it gets its own page.

Two characters, one shape

Unicode contains both µ (U+00B5 MICRO SIGN) and μ (U+03BC GREEK SMALL LETTER MU). The micro sign was inherited from the Latin-1 character set, where it sat among ° and ± so that typewriter-era documents could show units. The Greek letter is the real mu. They look identical in most fonts, and Unicode treats µ as a compatibility character that decomposes to μ, which means normalised text and many search engines already consider them the same. The practical advice: use µ for units when you type it with a keyboard shortcut, because that is what Alt + 0181 and Option + M produce, and use μ when you are writing Greek or mathematics, such as the mean μ of a distribution or the coefficient of friction. Never mix the two within a document, and when a lab or journal specifies one, follow it.

Common mistakes

The most consequential error is medical: µg (micrograms) mistaken for mg (milligrams) is a thousandfold dose difference, which is why prescribing guidelines in many countries ask for "mcg" or the full word instead of the symbol. In email and spreadsheets people also type "um" or "ug" when the symbol seems out of reach; that is acceptable in a filename but not in a label, a report or a datasheet. Do not use the capital M either, since M means mega, a factor of 10¹².

Typing it

Because µ lives in Latin-1, it has a real Windows Alt code (Alt + 0181) and a Mac shortcut (Option + M), and Word converts 00B5 to µ after Alt + X. In HTML the entity is µ. LaTeX users have several routes: \mu in maths mode gives the Greek letter, while siunitx offers \micro and \si{\micro\meter} for units in text. Phones are the weak point: neither the iPhone keyboard nor Gboard has a long-press for µ, so add the Greek keyboard, which gives you μ on the M key, or set a text replacement.

Beyond the lab

µ also appears in audio (the µ-law codec), in the name of the microkernel and in maker circles, where µC is shorthand for microcontroller. In bios, engineers and photographers use it in handles like "µ4/3" for Micro Four Thirds. Pair it with the ohm symbol and the degree symbol for a full set of unit signs, and see the sigma symbol page for another Greek letter that does double duty in statistics.

Micro Sign FAQ

What is the Alt code for the micro sign?

Hold Alt and type 0181 on the numeric keypad. This produces the Latin-1 MICRO SIGN in any Windows application. In Word, 00B5 followed by Alt + X gives the same character, and 03BC then Alt + X gives the Greek mu instead.

How do I type µ on a Mac?

Press Option + M. On macOS this shortcut inserts the micro sign (U+00B5), which is the correct character for units such as µm and µg.

Should I use µ or μ for micrograms?

Either is accepted, and compatibility normalisation (NFKC) folds the micro sign into the Greek letter. Keyboard shortcuts produce the micro sign µ, so it is the one most people use for units. If a journal or a lab style guide names μ, use that consistently instead.

Why do prescriptions write mcg instead of µg?

Handwritten or badly printed µg can be misread as mg, a thousand times larger. Patient-safety bodies in the US, UK and elsewhere therefore recommend "mcg" or "micrograms" in prescribing. In scientific writing, µg remains correct.

How do I get the micro symbol on my phone?

There is no long-press key for it. On the iPhone, add a text replacement in Settings → General → Keyboard so "mcr" expands to µ, or add the Greek keyboard and tap M. Gboard on Android works the same way with a Greek layout or a personal-dictionary shortcut.

Is there a space between the number and µm?

Yes, one normal space between the number and the unit (5 µm), and none between µ and m. That follows the SI rule for every prefixed unit: the prefix and unit form a single symbol.