Sigma — σ Greek Letter Symbol
σ
Sigma — σ / Σ
18th letter of the Greek alphabet · pronounced /ˈsɪɡmə/
MathematicsPhysicsEngineeringStatistics
Copy symbol
σ
Lowercase sigma
Σ
Uppercase Sigma
Technical reference
| Unicode (lowercase) | U+03C3 |
| Unicode (uppercase) | U+03A3 |
| HTML entity | σ |
| HTML decimal | σ |
| LaTeX | \sigma |
| Python / Unicode escape | \u03c3 |
| Alt code (Windows) | Alt + 963 |
Uses in science & engineering
Summation (Σ)
Uppercase Sigma is the universal symbol for summation of a series. Ubiquitous in all mathematical and engineering formulas.
\(\sum_{i=1}^{n} x_i = x_1 + x_2 + \ldots + x_n\)
Standard deviation
Measure of the spread or dispersion of a data set around its mean.
\(\sigma = \sqrt{\frac{1}{N}\sum_{i=1}^{N}(x_i – \mu)^2}\)
Normal stress
Stress component perpendicular to a cross-sectional plane. Fundamental in structural and mechanical engineering.
\(\sigma = \frac{F}{A}\)
Stefan–Boltzmann constant
Constant relating radiated power of a black body to temperature.
\(P = \sigma A T^4\)
Electrical conductivity
Reciprocal of resistivity; measure of how well a material conducts electricity.
\(\mathbf{J} = \sigma \mathbf{E}\)
Related symbols
How to insert in applications
Windows
Best option: copy from this page.
Or press Win + . to open emoji & symbols panel.
Alt codes work only in Word/Notepad with NumLock on and English layout — not in browsers.
Or press Win + . to open emoji & symbols panel.
Alt codes work only in Word/Notepad with NumLock on and English layout — not in browsers.
macOS
Press ⌃⌘Space → Character Viewer → search “sigma”
Microsoft Word
Type 03c3 then press Alt+X
Google Docs
Insert → Special characters → search by name
Excel
Insert → Symbol → Subset: Greek → select symbol
LaTeX
Use in math mode: $ … $
Python
Use Unicode escape or chr()
HTML / CSS
Use HTML entity or decimal code