Capital sigma Σ is the eighteenth Greek letter. Type 03A3 then Alt+X in Word. It is used for summation, though formal mathematics prefers the separate n-ary summation operator at U+2211. Lowercase σ is the standard deviation in statistics.
01 All shortcuts at a glance
| Platform | Shortcut | |
|---|---|---|
| Windows (any app) | Win+. or Win+; emoji/symbol picker, or Character Map (Win+R → charmap) |
|
| Mac | Control+Command+Space to open Character Viewer, search "Greek Capital Letter Sigma" |
|
| Word / Outlook | Type 03A3, then press Alt+X |
|
| Linux (IBus) | Ctrl+Shift+U, then 03a3, then Enter |
|
| HTML / CSS | Σ · \03a3 (CSS) |
02 Step by step, per platform
A real, followable procedure for every platform, not a thin restatement of the shortcut.
Windows
- Open Character Map: Win+R, type charmap, press Enter.
- Search or scroll for Greek Capital Letter Sigma (U+03A3).
- Select it, click Copy, then paste where you need it.
Mac
- Press Control+Command+Space to open the Character Viewer.
- Type "Greek Capital Letter Sigma" in the search field.
- Double-click the result to insert it.
Microsoft Word
- Type 03A3.
- Press Alt+X immediately after, it converts the hex code to Σ.
03 Characters in this set
04 Troubleshooting & confusables
| Looks like it | But it's actually | When to use |
|---|---|---|
| ∑ (U+2211) | N-ary summation, the maths operator | The correct character for a sum, with operator spacing and a taller glyph. |
| σ (U+03C3) | Lowercase sigma | For standard deviation and stress. Case carries meaning in notation. |
| ς (U+03C2) | Final sigma | Greek uses this form at the end of a word only. It is not a separate quantity. |
05 FAQ
What is the Unicode code point for sigma?
Capital sigma is U+03A3, lowercase is U+03C3, and the word-final form is U+03C2. The summation operator is separate at U+2211.
Should I use Σ or ∑ for a sum?
Use ∑ at U+2211 in typeset mathematics. It is taller, spaces as an operator, and carries the correct meaning. The Greek letter is what a Greek keyboard produces.
What does lowercase σ mean?
Standard deviation in statistics, and mechanical stress in engineering. A quantity described as three sigma lies three standard deviations from the mean.
Why does Greek have two lowercase sigmas?
The final form ς is used at the end of a word and σ everywhere else. It is a positional variant of one letter, much like a long s in older English printing.
What is Six Sigma?
A quality methodology named for a process so tightly controlled that defects fall six standard deviations from the mean. The name borrows the statistical symbol directly.