Guides · 5 min read
How to pronounce Greek letters in maths and science
English-speaking mathematicians and scientists use traditional English names for the 24 Greek letters, not the modern Greek ones, and several letters have two accepted pronunciations. The table gives each letter, how to say it and what it usually stands for. Each letter's own page has a recording and examples read aloud.
Updated 11 November 2026
All 24 letters
| Letter | Name | How to say it | Often stands for |
|---|---|---|---|
| α Α | Alpha | AL-fuh | the significance level of a test; the angles of a triangle; the fine-structure constant |
| β Β | Beta | BAY-tuh (US), BEE-tuh (UK) | the intercept and slope of a regression line; an asset's beta against the market |
| γ Γ | Gamma | GAM-uh | the Lorentz factor; rewards discounted by γ; the gamma function at a whole number |
| δ Δ | Delta | DEL-tuh | average velocity: change in position over change in time; the Kronecker delta when i = j; uncertainties in position and momentum |
| ε ϵ Ε | Epsilon | EP-sih-lon (UK also ep-SY-lun) | the error term; ε₀, the permittivity of free space; x lies within ε of a |
| ζ Ζ | Zeta | ZAY-tuh (US), ZEE-tuh (UK) | the sum of the reciprocals of the squares; an underdamped system, which oscillates |
| η Η | Eta | AY-tuh (US), EE-tuh (UK) | η sets the size of each step; the efficiency of a Carnot engine |
| θ Θ | Theta | THAY-tuh (US), THEE-tuh (UK) | θ is an angle; θ holds the model's parameters; grows at the rate n log n |
| ι Ι | Iota | eye-OH-tuh | an inclusion map sends each element to itself |
| κ Κ | Kappa | KAP-uh | the condition number of a matrix; the curvature of a circle of radius r |
| λ Λ | Lambda | LAM-duh | λ is an eigenvalue of A; wave speed equals wavelength times frequency; the Poisson distribution with rate λ |
| μ Μ | Mu | MYOO (rhymes with "few") | μ is the mean; friction is μ times the normal force |
| ν Ν | Nu | NYOO (UK), NOO (US) | the energy of a photon of frequency ν; kinematic viscosity |
| ξ Ξ | Xi | KSY or ZY (rhymes with "sky"), also KSEE | a random variable with mean zero; an underdamped system |
| ο Ο | Omicron | OM-ih-kron | Latin little-o: f grows more slowly than n |
| π Π | Pi | PIE | the area of a circle; the Gaussian integral |
| ρ Ρ | Rho | ROH | the correlation coefficient; density is mass over volume |
| σ Σ | Sigma | SIG-muh | the variance; the sigmoid function; capital sigma as a sum |
| τ Τ | Tau | TOW (rhymes with "cow"), also TAW | torque is the cross product of position and force; the time constant of a resistor–capacitor circuit |
| υ Υ | Upsilon | OOP-sih-lon or UP-sih-lon | the name of a family of mesons made of a bottom quark and its antiquark |
| φ Φ | Phi | FIE (rhymes with "pie"), also FEE | the golden ratio; the standard normal distribution function; magnetic flux through an area |
| χ Χ | Chi | KYE (rhymes with "sky") | the chi-squared statistic, observed against expected counts; the Euler characteristic of a polyhedron |
| ψ Ψ | Psi | SIGH (the p is usually silent in English), also PSY | the Schrödinger equation for ψ; the probabilities add up to one |
| ω Ω | Omega | oh-MAY-guh (US), OH-mig-uh (UK) | angular frequency from frequency; Ω counts the microstates |
The letters with two pronunciations
- Beta, zeta, eta and theta: “BAY-tuh, ZAY-tuh, AY-tuh, THAY-tuh” in American English and “BEE-tuh, ZEE-tuh, EE-tuh, THEE-tuh” in British English. Both are right; use the one your lecturers use.
- Phi: “FIE”, rhyming with “pie”, is usual in American mathematics; “FEE” is common in Britain and in physics.
- Xi: usually “KSY” or “ZY”, rhyming with “sky”. “KSEE” is closer to the Greek and is also heard.
- Psi: “SIGH” with a silent p is most common; some speakers keep the p, “PSY”.
- Chi: “KYE”, rhyming with “sky”. The ch is a k sound, not “chee”.
- Omega: “oh-MAY-guh” in American English, “OH-mig-uh” in British English.
Why only some capitals are used
Fourteen Greek capitals look the same as Latin letters: Α, Β, Ε, Ζ, Η, Ι, Κ, Μ, Ν, Ο, Ρ, Τ, Υ and Χ. A capital alpha would be read as an A, so these are almost never used as symbols. The ten capitals that look different do the work: Γ, Δ, Θ, Λ, Ξ, Π, Σ, Φ, Ψ and Ω.
Capital and lower-case forms of the same letter usually mean different things. Σ is a sum and σ a standard deviation; Π is a product and π the number 3.14159…; Δ is a change and δ a small quantity.
Variant shapes of the same letter
| Letter | Two shapes | In LaTeX | Said |
|---|---|---|---|
| Epsilon | ϵ and ε | \epsilon and \varepsilon | epsilon |
| Theta | θ and ϑ | \theta and \vartheta | theta |
| Phi | ϕ and φ | \phi and \varphi | phi |
| Rho | ρ and ϱ | \rho and \varrho | rho |
| Sigma | σ and ς (word-final) | \sigma and \varsigma | sigma |
| Pi | π and ϖ | \pi and \varpi | pi |
How Greek letters sound inside a formula
In a formula a Greek letter is read by its name, like any other letter: σ² is “sigma squared”, μ₀ is “mu naught”, Δx is “delta x”. Hear one in context:
X ∼ N(0, 1)
Aethel says
X is distributed as N of 0, 1
The symbol library covers the Greek alphabet and the other symbols of mathematics, each with its spoken name, meaning and LaTeX command.
Questions
Is it “bay-ta” or “bee-ta”?
Both. “BAY-tuh” is American and “BEE-tuh” is British. The same split applies to zeta, eta and theta.
How do you pronounce ξ?
Most English-speaking mathematicians say “ksy” or “zy”, rhyming with “sky”. “Ksee” is closer to the Greek. See the page for xi.
Should I pronounce Greek letters the way Greeks do?
Not in English-language maths and science. The English names are the convention: “pie” for π, not “pee”. Greek speakers, and speakers of other languages, use their own names.
How do I type Greek letters?
In LaTeX each has a command: \alpha, \beta, \Gamma and so on. Each letter's page lists its command and its Unicode code point for other software.