Sigma Symbol (Σ σ ς): How to Type It Everywhere

Short answer: Tap a sigma below to copy it. To type it: on Windows, Alt + 931 = Σ, Alt + 963 = σ (numeric keypad); on Mac, Option + W = ∑ (summation), or use the Character Viewer for Greek Σ/σ; in Word, type 03A3 then Alt + X; in HTML use Σ / σ; in LaTeX use \Sigma / \sigma (and \sum for the operator).

Sigma is the 18th Greek letter — see the whole set in the Greek alphabet guide, or get any letter’s codes from the Alt Code Finder.

Sigma (Σ uppercase, σ lowercase) is the 18th letter of the Greek alphabet, and it does double duty in maths and science: uppercase Σ means “sum”, lowercase σ means “standard deviation.” There’s also a special third form and a look-alike operator, so let’s sort those out.

Σ vs ∑ — the letter and the operator

Two characters look almost the same:

Σ — Greek capital sigma (U+03A3). The letter. Fine to use as the summation sign in ordinary text.
∑ — the n-ary summation operator (U+2211). A dedicated maths character; in typeset maths it renders larger and takes limits above and below. It’s what a Mac types with Option + W.

In everyday writing they’re used interchangeably, but in proper typesetting the operator ∑ (LaTeX \sum) is preferred for summations, while Σ (\Sigma) is the letter.

Greek capital sigma compared with the summation operator

The three sigmas

Lowercase sigma has two shapes:

σ — the normal lowercase, used everywhere in maths and science.
ς — the final sigma, used only at the end of a word in Greek text. It has no mathematical meaning.
Σ — the uppercase.

Quick reference

Symbol	Name	Windows	Mac	HTML	LaTeX	Unicode
Σ	Greek capital sigma	Alt + 931	Viewer / Greek input	`Σ`	`\Sigma`	U+03A3
σ	Greek small sigma	Alt + 963	Viewer / Greek input	`σ`	`\sigma`	U+03C3
ς	Final sigma	Alt + 962	Viewer	`&sigmaf;`	`\varsigma`	U+03C2
∑	Summation operator	Alt + 8721	Option + W	`∑`	`\sum`	U+2211

Type sigma on Windows

Alt codes: hold Alt, type on the numeric keypad (Num Lock on): Alt + 931 → Σ, Alt + 963 → σ, Alt + 962 → ς, Alt + 8721 → ∑. Use a Unicode-aware app (Word, browsers, email).
Word: type 03A3 and press Alt + X for Σ, 03C3 + Alt + X for σ, or 2211 + Alt + X for ∑. In an equation (Alt + =), type \Sigma, \sigma, or \sum then Space.
Lots of Greek: add the Greek keyboard and switch with Windows + Space.

Type sigma on Mac

∑ (summation): press Option + W — the quickest sigma on a Mac.
Greek Σ / σ / ς: open the Character Viewer with Control + Command + Space, search “sigma,” and double-click the form you need; or add the Greek input source (the “s” key gives σ).

Sigma in Word & Excel

Word: the 03A3 + Alt + X method above, or Insert → Symbol → (Greek and Coptic); for a summation with limits, use an equation and \sum.
Excel — watch this one: pressing Alt + = in Excel inserts the AutoSum (SUM) function, not the Σ character. To put the actual Σ symbol in a cell or chart, use Insert → Symbol, type 03A3 in the “Character code” box (from: Unicode hex), and Insert — or paste Σ from the tool above.

Sigma in HTML & LaTeX

HTML: Σ → Σ, σ → σ, &sigmaf; → ς; numeric fallbacks Σ / σ / ς work too.
LaTeX (math mode): \Sigma (letter), \sigma (letter), \varsigma (ς). For a summation use \sum, e.g. \sum_{i=1}^{n} — it renders as the large operator with limits, which \Sigma does not.

Type sigma on Linux & phone

Linux: Ctrl + Shift + U, then 03a3 (Σ), 03c3 (σ) or 03c2 (ς), then Enter.
Phone: add a Greek keyboard (iPhone: Settings → General → Keyboard; Android: Gboard languages) and switch with the globe key, or copy σ/Σ from the tool above.

What sigma means

Summation (Σ / ∑) — the sum of a series: Σxᵢ adds every xᵢ, with start and end values written below and above.
Standard deviation (σ) — in statistics, σ is the population standard deviation, a measure of spread; σ² is the variance. (Note: lowercase s is the sample standard deviation — keep them distinct.)
Six Sigma — the quality-management methodology.
Science & engineering — σ also denotes stress, electrical conductivity, surface charge density and the Stefan–Boltzmann constant; a sigma bond in chemistry.
Casually, “sigma” has taken on internet slang meanings unrelated to the maths.

Troubleshooting

Problem	Fix
Alt + 931 gives the wrong character	Use the numeric keypad with Num Lock on, in a Unicode-aware app.
Σ shows as a box ▯	Font lacks the glyph — switch to Segoe UI, Arial or Cambria Math. See symbol showing as a box.
Alt + = in Excel made a SUM formula, not Σ	That’s AutoSum. For the Σ character use Insert → Symbol (03A3) or paste.
σ looks like an “o”	It’s the Greek lowercase sigma (U+03C3); keep it distinct from the Latin o and omicron ο.
Summation looks small in my document	Use the operator ∑ (LaTeX `\sum`), not the letter Σ, for typeset limits.

Recap

Windows → Alt + 931 (Σ) / Alt + 963 (σ); ∑ = Alt + 8721; Word: 03A3 + Alt + X.
Mac → Option + W (∑); Character Viewer for Greek Σ/σ/ς.
Web → Σ / σ. LaTeX → \Sigma / \sigma, \sum for summation.
Excel → Insert → Symbol (03A3) or paste — Alt + = is AutoSum, not Σ.

Frequently asked questions

What does the sigma symbol mean?

Sigma is the 18th letter of the Greek alphabet, written Σ (uppercase) and σ (lowercase). In maths, uppercase Σ means summation — the sum of a series of terms — while lowercase σ means standard deviation in statistics. It also appears for stress, conductivity and other quantities in science.

What’s the difference between Σ and ∑?

Σ (U+03A3) is the Greek capital letter sigma, and ∑ (U+2211) is the mathematical summation operator. They look almost identical and are often used interchangeably, but in typeset maths the operator ∑ renders larger with limits above and below, which is why LaTeX uses \sum for summations and \Sigma for the letter.

How do I type sigma on Windows?

Hold Alt and type on the numeric keypad: 931 for Σ, 963 for σ, 962 for ς, or 8721 for the summation operator ∑, in a Unicode-aware app. In Word, you can also type 03A3 (or 03C3) and press Alt + X, or use \sum in an equation.

How do I type sigma on a Mac?

Press Option + W for the summation operator ∑. For the Greek capital Σ, lowercase σ or final ς, open the Character Viewer with Control + Command + Space and search “sigma,” or add the Greek input source, where the “s” key gives σ.

What is the final sigma (ς)?

ς is the final sigma, used only when sigma falls at the end of a word in Greek text; σ is used everywhere else. It has no mathematical meaning. Its code is Alt + 962, the HTML entity is &sigmaf;, and in LaTeX it’s \varsigma.

What does σ mean in statistics?

Lowercase σ is the population standard deviation, which measures how spread out a data set is around its mean; σ² is the variance. It’s distinct from the sample standard deviation, which is written with a lowercase Latin s.

Written by Igor R.. Tested on Windows 11, macOS, Word, Excel and LaTeX. Symbol code points follow the Unicode Standard. Last updated July 2026.