Get the Sigma symbol in both uppercase (Σ) and lowercase (σ) forms. Easy to copy and paste, with complete information about usage and meaning.
Uppercase Sigma
Lowercase Sigma
U+03A3 Σ \Sigma The uppercase Sigma (Σ) is the 18th letter of the Greek alphabet. In mathematics, it's widely used as the summation operator to represent the sum of a sequence. When used for summation, it includes an index variable and bounds indicating the range of values to sum.
Σ(i=1 to n) x_i Represents the sum of all x_i where i goes from 1 to n
U+03C3 σ \sigma U+03C2 U+03F2 The lowercase sigma (σ) is commonly used in statistics to represent standard deviation and in physics to denote electrical conductivity. In statistics, σ represents the population standard deviation, while s represents the sample standard deviation.
σ = √(Σ(x - μ)²/N) Where μ is the mean and N is the population size
The Sigma symbol originated from the Phoenician letter "Shin" (𐤔), which represented the /ʃ/ sound. As it was adopted into the Greek alphabet, it evolved into the current Σ form. The symbol's use as a mathematical summation operator was introduced by Leonhard Euler in the 18th century, revolutionizing mathematical notation.
In ancient Greek inscriptions, three forms of Sigma were used: Σ, C (lunate sigma), and Ϲ (rounded sigma). The modern lowercase σ developed during the Middle Ages from a cursive form of the lunate sigma.
Discover how Sigma is used across different fields of science and mathematics
The primary use of Σ in mathematics is for summation notation. It represents:
Σⁿᵢ₌₁ i = 1 + 2 + ... + n Σⁿᵢ₌₁ (a + (i-1)d) Σⁿᵢ₌₁ arⁱ⁻¹ Σ∞ₙ₌₀ xⁿ Σᵢ Σⱼ aᵢⱼ Key applications in statistical analysis:
σ = √(Σ(x - μ)²/N) Complete list of Greek letters with easy copy functionality
| Name | Uppercase | Lowercase |
|---|---|---|
| Alpha | ||
| Beta | ||
| Gamma | ||
| Delta | ||
| Epsilon | ||
| Zeta | ||
| Eta | ||
| Theta | ||
| Iota | ||
| Kappa | ||
| Lambda | ||
| Mu | ||
| Nu | ||
| Xi | ||
| Omicron | ||
| Pi | ||
| Rho | ||
| Sigma | ||
| Tau | ||
| Upsilon | ||
| Phi | ||
| Chi | ||
| Psi | ||
| Omega |
Everything you need to know about the Sigma symbol
Σ (uppercase) and σ (lowercase) serve different purposes. The uppercase Σ is primarily used as a summation operator in mathematics to represent the sum of a sequence. The lowercase σ is commonly used in statistics to represent standard deviation and in physics for electrical conductivity.
The lowercase sigma has two forms: σ and ς. The ς form (called final sigma) is only used when sigma appears at the end of a Greek word. The σ form is used in all other positions. This distinction is only relevant when writing Greek text, not in mathematical or scientific notation.
In LaTeX, you can type Σ using \Sigma for the uppercase and \sigma for the lowercase. For summation notation, use \sum. For example: \sum_{i=1}^{n} x_i will produce a summation from i=1 to n of x_i.
In mathematics, Σ represents summation - adding up a sequence of numbers. When you see Σ with numbers above and below it (like Σⁿᵢ₌₁), it means to add up all values from the starting number (i=1) to the ending number (n). For example, Σ⁵ᵢ₌₁ i means 1 + 2 + 3 + 4 + 5 = 15.
In statistics, σ (lowercase sigma) represents the population standard deviation, which measures how spread out numbers are in a dataset. It's different from 's' which represents sample standard deviation. The formula for σ is the square root of the variance: σ = √(Σ(x - μ)²/N), where μ is the mean and N is the population size.
Yes! You can copy the Sigma symbols (Σ σ) directly from our website. For word processors, you can also insert them through the symbol menu. In Microsoft Word, go to Insert → Symbol → Greek. For Google Docs, use Insert → Special characters and search for "sigma".
The use of Σ for summation was introduced by Leonhard Euler in the 18th century. It was chosen because it's the first letter of the word "sum" in Greek (σύνολο, "súnolo"). This notation has become standard in mathematics due to its clarity and convenience in representing series and sequences.
There is no mathematical difference between Σ and ∑. They are the same symbol written in different fonts or styles. Σ is the Greek letter sigma, while ∑ is the mathematical n-ary summation operator. In practice, they are used interchangeably for summation notation.