24, alpha to omega
Greek Alphabet Reference
The 24 letters of the Greek alphabet, with their uppercase and lowercase forms, their names, and the fields that borrow them.
At a glance
Key factsLetters
First vowels
First true alphabet
Descendants
Latin and Cyrillic
Everyday use
Math, physics, science
The 24 Greek letters
24 rows| Upper | Lower | Name | Common use |
|---|---|---|---|
| A | α | Alpha | Angle, coefficient |
| B | β | Beta | Angle, beta particle |
| Γ | γ | Gamma | Gamma ray, constant |
| Δ | δ | Delta | Change, difference |
| E | ε | Epsilon | Small quantity |
| Z | ζ | Zeta | Damping ratio |
| H | η | Eta | Efficiency |
| Θ | θ | Theta | Angle |
| I | ι | Iota | A tiny amount |
| K | κ | Kappa | Curvature |
| Λ | λ | Lambda | Wavelength |
| M | μ | Mu | Micro prefix, mean |
| N | ν | Nu | Frequency |
| Ξ | ξ | Xi | Random variable |
| O | ο | Omicron | Rarely used alone |
| Π | π | Pi | Circle constant |
| P | ρ | Rho | Density |
| Σ | σ | Sigma | Sum, deviation |
| T | τ | Tau | Time constant |
| Υ | υ | Upsilon | Physics particle |
| Φ | φ | Phi | Golden ratio, angle |
| X | χ | Chi | Chi-squared test |
| Ψ | ψ | Psi | Wave function |
| Ω | ω | Omega | Ohms, angular speed |
Where it comes from
The Greek alphabet took shape around the ninth century BCE, when Greeks adapted the Phoenician consonant script and, crucially, added dedicated letters for vowels. That made it the first alphabet in the modern sense, and it became the direct ancestor of the Latin and Cyrillic alphabets. The same 24 letters are still written today, in Greece for the modern language and everywhere else as a shared pool of symbols for mathematics, physics, engineering, and the sciences.
How to use it
Read each row as a pair: the capital form on the left, the small form beside it, then the name you say aloud. Many letters carry fixed meanings by convention. Pi is the circle constant, sigma marks a sum in its capital form and standard deviation in its lowercase form, theta is an angle, lambda a wavelength, and delta a change or difference. When you meet a Greek letter in a formula, its name is usually the fastest way to look up what it stands for, so knowing the names matters as much as recognizing the shapes.
This page is a standing reference at a fixed URL, built to be linked and cited. The data here is compiled from the standard Greek alphabet as used in mathematics, science, and modern Greek.