Sigma Symbol Σ σ — Copy, Paste and Type It
The sigma symbol is the 18th letter of the Greek alphabet, written σ in lowercase and Σ in uppercase. It is pronounced /ˈsɪɡmə/ (“SIG-muh”). Click a symbol to copy it.
Sigma is the only Greek letter with two lowercase forms — and its capital has a look-alike math operator. All four characters are below, with a note on exactly when to use each.
Copy the sigma symbol
Dashed boxes are look-alikes that are not the Greek letter — listed so you can tell them apart.
Σ σ ς ∑ — three sigmas and one that isn’t
| Character | Unicode name | Code point | When to use it |
|---|---|---|---|
| Σ | Greek capital letter sigma | U+03A3 | The capital letter, in Greek words, names and variables |
| σ | Greek small letter sigma | U+03C3 | The lowercase letter at the start or middle of a word, and standard deviation |
| ς | Greek small letter final sigma | U+03C2 | Only at the end of a word, as in λόγος |
| ∑ | N-ary summation | U+2211 | The math sum operator — not a letter |
Σ vs ∑: they look alike, but anyone writing a formula should use ∑ (U+2211), and anyone writing Greek or an alphabet should use Σ (U+03A3). The sum sign is designed to stretch, take limits above and below, and be read as an operator by screen readers and equation software. In LaTeX this is the difference between \Sigma (the letter) and \sum (the operator).
σ vs ς: Greek spelling uses ς only as the last letter of a word and σ everywhere else — ΣΟΦΟΣ becomes σοφός in lowercase. In LaTeX, the final form is \varsigma. In mathematics, only σ is used.
Typing them: Alt + 228 types Σ and Alt + 229 types σ on Windows. On a Mac, Option + W types the sum sign ∑ — not the letter Σ. On a Greek keyboard, the W key types ς.
Not sure which Greek letter you need? See all 24 Greek symbols with codes.
Sigma codes — Unicode, HTML, LaTeX and Alt codes
| Char | Unicode | HTML entity | HTML decimal | HTML hex | CSS | JavaScript | LaTeX | Windows | Mac |
|---|---|---|---|---|---|---|---|---|---|
| σ | U+03C3 | σ | σ | σ | \03C3 | \u03C3 | \sigma | Alt + 229 | Greek keyboard S |
| Σ | U+03A3 | Σ | Σ | Σ | \03A3 | \u03A3 | \Sigma | Alt + 228 | Greek keyboard Shift + S |
| ς | U+03C2 | ς | ς | ς | \03C2 | \u03C2 | \varsigma | 03C2 then Alt + X (Word) | Character Viewer |
| ∑ | U+2211 | ∑ | ∑ | ∑ | \2211 | \u2211 | \sum | 2211 then Alt + X (Word) | Option + W |
| ϲ | U+03F2 | — | ϲ | ϲ | \03F2 | \u03F2 | — | 03F2 then Alt + X (Word) | Character Viewer |
Need the characters without any explanation? Open the Greek letters copy-paste sheet.
How to type the sigma symbol
Windows
- Fastest: press
Win + .to open the emoji panel, choose the Symbols tab (Ω), then Greek. -
Alt code: hold
Altand type229for σ or228for Σ on the numeric keypad with Num Lock on. - Microsoft Word: type
03C3and pressAlt + Xfor σ;03A3thenAlt + Xfor Σ. Word converts it in place.
Mac
- Add the Greek keyboard in System Settings → Keyboard → Input Sources, then
Stypes σ andShift + Stypes Σ.Wtypes the final ς. Option + Won the standard keyboard types ∑ (N-ary summation, U+2211).- Or open the Character Viewer with
Ctrl + Cmd + Spaceand search “sigma”.
iPhone and Android
- iOS: Settings → General → Keyboard → Keyboards → Add New Keyboard → Greek. Tap the globe key to switch.
- Android (Gboard): Settings → Languages → Add keyboard → Greek.
- Or copy the character from the top of this page.
LaTeX
\sigma— lowercase σ in math mode\Sigma— capital Σ\varsigma— ς (greek small letter final sigma)\sum— ∑ (n-ary summation)
HTML, CSS and code
- HTML:
σorσorσ - CSS:
content: "\03C3"; - JavaScript / JSON:
"\u03C3"— Python:"\u03c3" - In source code, prefer the escape over the pasted glyph — it survives every file encoding.
Full typing guide for every platform, including Linux and Google Docs → how to type Greek letters.
What does sigma mean?
Statistics
- σ — population standard deviation; the sample version is the Latin letter s
- σ² — variance
- Σ — a covariance matrix
Mathematics
- ∑ — summation: ∑ xi adds up every x
- σ(n) — the sum of the divisors of n
- σ-algebra — a family of sets in measure theory
Chemistry
- σ bond — a covalent bond formed by head-on overlap, as opposed to a π bond
- σ — the shielding constant in NMR
Physics & engineering
- σ — normal stress in a material
- σ — electrical conductivity, and surface tension
- σ — the Stefan–Boltzmann constant
Business & culture
- Six Sigma — a quality-management method aiming at 3.4 defects per million
- “sigma” — internet slang for a self-reliant lone wolf, which is behind many recent searches for the symbol
- Σ on campus — Sigma fraternities and sororities
Sigma at a glance
- Position
- 18th of 24
- Uppercase / lowercase
- Σ σ
- Greek name
- σίγμα
- Pronunciation
- /ˈsɪɡmə/
- Numeric value
- 200
- Became
- Latin S and Cyrillic С
Frequently asked questions
What is the sigma symbol?
Sigma (Σ σ) is the 18th letter of the Greek alphabet, pronounced /ˈsɪɡmə/ (“SIG-muh”). It is most often used for standard deviation, summation.
How do I type the sigma symbol on a keyboard?
On Windows, press Win + . → Symbols → Greek, or in Microsoft Word type 03C3 and press Alt + X; the classic Alt code Alt + 229 types σ and Alt + 228 types Σ. On a Mac, switch to the Greek keyboard and press S (Shift + S for the capital). Or simply copy it from the top of this page.
What is the LaTeX command for sigma?
Use \sigma for lowercase σ and \Sigma for capital Σ, inside math mode: $\sigma$.
What is the Unicode and HTML code for sigma?
Lowercase σ is U+03C3, written in HTML as σ or σ. Capital Σ is U+03A3, written Σ or Σ.
What does σ mean in statistics?
σ (lowercase sigma) is the population standard deviation, and σ² is the variance. The sample standard deviation is written with the Latin letter s.
Is the sum symbol ∑ the same as Σ?
No. ∑ (U+2211) is the summation operator used in math; Σ (U+03A3) is the Greek capital letter sigma. They look similar, but formulas should use ∑ (\sum in LaTeX).
What is ς?
ς (U+03C2) is the final form of lowercase sigma. In Greek it is used only at the end of a word; σ is used everywhere else.