Symbols

Sigma Symbol (Σ / σ): How to Type, Copy, and Use It

ByGlenda Jnku

Copy and paste the sigma symbol

Sigma in its forms, with the codes you’re likely to need. Use the grid above to copy with one click; this table is the reference.

Symbol	Name	Unicode	Windows	HTML
Σ	Greek capital sigma	U+03A3	Alt + 931	Σ
σ	Greek small sigma	U+03C3	Alt + 963	σ
ς	Greek final sigma	U+03C2	Alt + 962	ς
∑	summation operator	U+2211	Alt + 8721	∑

None of these are on a standard keyboard, so each takes a shortcut, a code, or a copy. The sections below cover each device, then the two lowercase forms that make sigma unusual.

How to type the sigma symbol on any device

Type Σ on Windows

Use the Alt code: turn on Num Lock, hold Alt, and type 931 on the numeric keypad for Σ, or 963 for σ (and 962 for the final ς). On a laptop with no keypad, press Windows + . and search “sigma.”

Type Σ on Mac

The Mac has no dedicated sigma key. Open the Character Viewer with Control + Command + Space and search “sigma,” or add a Greek keyboard in System Settings, where σ sits on the S key and Σ is Shift + S.

Type Σ on iPhone and Android

Add a Greek keyboard in settings and sigma is on the S key (Σ with Shift). Otherwise copy it from the grid above. Some maths and scientific-calculator keyboards also include Σ and σ.

Type Σ in Microsoft Word

Type 03A3 then press Alt + X for Σ (use 03C3 for σ, or 03C2 for ς). Or use Insert → Symbol, where the Greek letters are listed. In the equation editor (Alt + =), \Sigma and \sigma work.

Type Σ on Linux

Press Ctrl + Shift + U, type 03a3, then Enter for Σ (03c3 for σ, 03c2 for ς). A Greek keyboard layout also puts sigma on the S key.

Add Σ in HTML and CSS

In HTML, Σ is Σ (capital) or σ (lowercase), the final ς is ς, or the numeric Σ. In CSS, a Σ in a content value is the escaped code point \03A3.

The two lowercase sigmas: σ and the final ς

Sigma has a feature almost no other letter has: two lowercase forms, and which you use depends on where the letter sits in a word. The normal σ is used at the start or in the middle of a word, but at the very end of a word it changes to ς (the “final sigma,” with a little tail). So the Greek word for earthquake, σεισμός, begins with σ and ends with ς — same letter, two shapes.

This trips up anyone typing Greek or setting a Greek word: if you use a plain σ at the end of a word, a Greek reader immediately sees it as wrong, like writing an English word with a capital in the middle. The capital Σ has no such split — there’s only one uppercase form. It’s a small rule, but it’s the thing that separates someone who’s really typing Greek from someone who’s just dropping in a sigma, so the final ς is in the grid above for when you need it.

Position in word	Use	Example
start / middle	σ	σῶμα
end of word	ς	ἔρως
capital (anywhere)	Σ	ΣΙΓΜΑ

What sigma stands for: statistics, sums, and science

Sigma is one of the busiest letters in technical writing, and the case usually tells you which meaning is intended. The capital Σ most often means a sum (the summation operator), while the lowercase σ has a cluster of specialist jobs. In statistics, σ is the standard deviation — how spread out data is — and σ² is the variance.

Beyond stats, lowercase σ pops up all over science: it’s electrical conductivity in physics, stress in engineering (force per area), the Stefan–Boltzmann constant in thermodynamics, and a sigma bond in chemistry. The capital Σ, outside of sums, can denote a sum type in programming or a summation in a covariance matrix. So when you meet a sigma, glance at the case and the context: capital usually means “add these up,” lowercase usually means “spread, stress, or a physical constant.”

Form	Field	Means
σ	statistics	standard deviation
σ	engineering	stress
σ	physics	conductivity
Σ	maths	a sum

Six Sigma and ‘sigma’ as internet slang

Sigma has escaped the classroom in two very different directions. The older one is Six Sigma, a quality-management method born at Motorola in the 1980s and made famous by General Electric. It’s named after the σ of standard deviation: a “six sigma” process keeps defects six standard deviations away from the average, which works out to fewer than four faults per million. In business, calling something “six sigma” is shorthand for near-flawless.

The newer one is internet slang. Around 2021, “sigma male” spread online as a label for a supposed lone-wolf personality type, and “sigma” drifted into general Gen Alpha slang meaning cool, impressive, or admirable (“that’s so sigma”). It’s mostly used jokingly or ironically now. Whatever you make of the trend, it’s why a Greek letter that means “standard deviation” also turns up in memes — the same three letters, a very different audience.

Σ the letter vs ∑ the summation operator

Worth a quick note, because it’s a common mix-up: the Greek capital sigma Σ (U+03A3) and the summation operator ∑ (U+2211) are different characters that look nearly identical. For a real sum in maths, the operator ∑ is the correct one — it’s sized for equations and read as “summation” by software. The Greek Σ is the letter. In casual use people type Σ for sums all the time and it’s understood, but the precise character is ∑.

Because that distinction has its own details — how to read the index and limits, how to do a sum in code — it gets a full treatment in the summation symbol guide. Sigma’s cousins delta and pi have the same letter-vs-operator story, covered in the delta symbol and pi symbol guides.

Sigma in the Greek alphabet (and how it became S)

Sigma is the eighteenth letter of the Greek alphabet, and it sounds like our S — which is no accident. Greek borrowed its alphabet from the Phoenicians, whose letter shin (an “sh”/”s” sound) became sigma; the same Phoenician letter, passed to the Romans, gave us the Latin S. So Σ and S are long-lost cousins, both descendants of a Phoenician character from around 3,000 years ago.

The name “sigma” itself likely comes from a Greek word meaning “to hiss,” a nod to the sound it makes. That deep history is why the letter feels so natural in scientific notation — it’s been carrying the “s” sound (for “sum,” “standard deviation,” “stress”) across three writing systems and three millennia.

Σ in URLs and encoding

In a URL, Σ is percent-encoded as %CE%A3 (its two UTF-8 bytes); lowercase σ is %CF%83 and the summation ∑ is %E2%88%91. In code, the escape for the character in a string is \u03A3 for Σ and \u03C3 for σ. If Σ ever shows as garbled characters or a box, the page is being read in the wrong encoding — serve it as UTF-8.

Copy-paste HTML codes

Every code for the sigma letters and the summation sign in one place. Click a cell and copy.

Symbol	Named entity	Numeric entity	URL (percent) code
Σ	Σ	Σ	%CE%A3
σ	σ	σ	%CF%83
ς	ς	ς	%CF%82
∑	∑	∑	%E2%88%91

In a CSS content value, use \03A3 for Σ. For the summation operator in depth, see the [summation symbol](/summation-symbol/) guide, and for every Greek letter the [math symbols Alt codes](/math-symbols-on-keyboard-alt-codes/) reference.

Troubleshooting

My Σ shows as a box or garbled text

That’s an encoding mismatch: the UTF-8 bytes for Σ are being read as an older encoding. Set the file, database, and page charset to UTF-8 and Σ displays correctly.

My Greek word ends in the wrong sigma

Greek uses σ inside a word and ς at the end. If a word finishes with a plain σ, swap it for the final ς (Alt + 962, or 03C2 then Alt + X), or copy ς from the grid above.

Should I use Σ or ∑ for a sum?

For a real sum, the summation operator ∑ (U+2211) is the precise character. The Greek capital Σ (U+03A3) is widely used and understood for sums too, but ∑ is sized for equations and recognised as “summation.”

FAQ

How do I type the sigma symbol?

On Windows, hold Alt and type 931 for Σ (963 for σ). In Word, type 03A3 then Alt + X. On a Mac, use the Character Viewer or a Greek keyboard. In HTML, write Σ. Or click Σ in the grid above.

Why does Greek have two lowercase sigmas?

Greek uses σ at the start or in the middle of a word and ς (the final sigma) at the end. So σεισμός starts with σ and ends with ς. The capital Σ has only one form.

What does σ mean in statistics?

Lowercase σ is the standard deviation, a measure of how spread out data is, and σ² is the variance. The capital Σ usually means a sum. Six Sigma, the quality method, is named after this σ.

What does ‘sigma’ mean as slang?

Online, “sigma” (as in “sigma male” or “that’s so sigma”) is recent slang for cool, admirable, or a lone-wolf type, usually used jokingly. It’s unrelated to the letter’s maths meaning — just the same word.

How do I write Σ in HTML?

Use Σ (capital) or σ (lowercase); the final ς is ς. In a URL, Σ is percent-encoded as %CE%A3.