How to type Capital Sigma
To type Capital Sigma (Σ), press Alt + 228 on Windows, holding Alt while typing the digits on the numeric keypad, or press Option + W on Mac, or write Σ in HTML. On any system you can copy it from this page, or enter its codepoint U+03A3 directly: Ctrl+Shift+U then 03a3 on Linux, or 03a3 then Alt+X in Microsoft Word.
Greek Capital Letter Sigma
- Copy it
- Unicode
- U+03A3
- Windows
- Alt + 228
| Where | Shortcut | How |
|---|---|---|
| Windows | Alt + 228 | Hold Alt and type the number on the numeric keypad. |
| Mac | Option + W | Press the keys together. |
| HTML | Σ | Paste this into HTML source. |
| Unicode | U+03A3 | GREEK CAPITAL LETTER SIGMA |
Other greek symbols
Capital Sigma is not the only name it goes by. People look for Σ as sum and summation as well, and the search box on this site matches any of them, so you do not have to know which name Unicode chose.
Σ lives in the Greek and Coptic block (U+0370-U+03FF), the Greek alphabet, used throughout mathematics and the sciences. Within Unicode it is classified as Lu, an uppercase letter. It has a lowercase counterpart and changes under case conversion. Its bidirectional class makes it left-to-right.
Its lowercase counterpart is σ (U+03C3). They are separate codepoints, so a byte comparison treats them as different characters even though a case-insensitive search does not.
How to type Σ in Microsoft Word
In Microsoft Word, type 03a3 and press Alt + X. Word reads the four characters before the cursor as a hex codepoint and replaces them, and pressing Alt + X again turns Σ back into 03a3, which is the quickest way to check what a character really is.
What Capital Sigma is used for
In mathematical notation Σ is a variable: it stands for a quantity rather than acting on one, so an equation treats it the way it treats x, and the spacing around it is the spacing around a letter. That is the classification unicode-math gives it, and it is what decides how the symbol is set: $\mupSigma$ in LaTeX, in maths mode rather than in a sentence.
The command is \mupSigma rather than the \Sigma most people reach for, and the difference is not cosmetic: mup is unicode-math for maths, upright, and this codepoint is the upright letter. Plain LaTeX's short command gives the sloped math-italic letter, which is a different character with a different codepoint. Copying Σ into an equation gets you the upright one.
Σ is a letter before it is a symbol, and on the Greek keyboard layout it is simply Shift and S: the key your keycap already calls S. That is the route when you are typing Greek rather than reaching for one character. How to type Greek on a keyboard has the whole map.
What Σ gets confused with
Σ has a twin that is a different character underneath. Search, sorting and anything that compares strings can tell them apart even where a reader cannot.
∑ (U+2211) is the n-ary summation operator. That is the one mathematics wants: it takes limits above and below, and a screen reader announces it as a sum where it announces this one as a letter.
What Unicode says about Capital Sigma
The code chart points from Σ to Summation and latin capital letter esh (U+01A9). These are the characters the standard thinks you might have meant instead, which makes them the ones worth checking when Capital Sigma looks nearly right but not quite.
How Capital Sigma behaves in software
Σ is East Asian Ambiguous: one column in a Western locale and two in a CJK one. That is why a table that lines up on your machine can break on somebody else's, with no change to the text at all. It is a left-to-right character, so it holds that direction even inside a right-to-left paragraph.
What people ask about Capital Sigma
Where to find summation symbol in word?
In Word, type 03a3 and press Alt+X, which converts the codepoint you just typed into Σ. Insert › Symbol › More Symbols finds it by its Unicode name, GREEK CAPITAL LETTER SIGMA. Google Docs has no Alt+X, so use Alt + 228 there, or Insert › Special characters and search the same name.
What is the symbol of sum in math?
Σ is GREEK CAPITAL LETTER SIGMA, encoded at U+03A3. It is distinct from latin capital letter esh (U+01A9) and n-ary summation (U+2211), which the chart lists beside it precisely because they are confused for one another.
What is the sum symbol called?
Unicode calls Σ GREEK CAPITAL LETTER SIGMA, at U+03A3. It is also searched for as sum, summation.
Every way to write Capital Sigma
| Form | Value |
|---|---|
| Codepoint | U+03A3 |
| Decimal | 931 |
| UTF-8 bytes | CE A3 |
| UTF-16 bytes | 03 A3 |
| HTML entity | Σ |
| HTML numeric | Σ or Σ |
| CSS | \03A3 |
| JavaScript | \u03A3 |
| Python | \u03A3 |
| URL-encoded | %CE%A3 |
| LaTeX, in maths mode | $\mupSigma$ |
| SVG | 03A3.svg · (SIL Open Font License) |
If Σ arrives as Σ
That is this exact character, undamaged: its two UTF-8 bytes CE A3 are being read one at a time as Windows-1252. The Latin-1 range is where this happens most, because it is the range every legacy system thought it already handled. Nothing is lost, and retyping will not help: the fix is at the reading end, which has to be told the text is UTF-8. An empty rectangle is the opposite complaint, and means the encoding is right and the font has no glyph for U+03A3.