Theta in LaTeX

The LaTeX command for theta (θ) is \theta. The capital form Θ is \Theta.

\theta

Greek Lowercase · Unicode θ (U+03B8) · no package needed

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Which command should you use?

Command	Package	Use it when
`\theta` recommended	none	Angles, model parameters.
`\vartheta`	none	Cursive variant, for a second angle or a different parameter.
`\Theta`	none	Capital: tight bound Theta(n), a parameter space.
`\hat{\theta}`	none	An estimator of theta.

Table 1. Ways to write theta in LaTeX. Every line was compiled with pdfLaTeX (TeX Live 2026) loading only the package shown.

Common mistake. Big-Theta notation uses the capital, \Theta(n log n); the lowercase \theta(n) is a function named theta.

How to type Theta

Write \theta inside math mode, that is between $…$ for inline math or in a \[ … \] or equation block for display math. It is part of core LaTeX math, so no extra package is required.

Example

$x = r\cos\theta, \quad y = r\sin\theta$

x = r\cos\theta, \quad y = r\sin\theta

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Related Greek Lowercase symbols

\beta\gamma\delta\epsilon\varepsilon\zeta\eta\vartheta\iota\kappa\varkappa\lambda\mu\nu

Lowercase Greek letters in LaTeX: the full table or search all 350+ LaTeX symbols.

FAQ

How do you write theta (θ) in LaTeX?

Use \theta in math mode; it needs no extra package. For example, $x = r\cos\theta, \quad y = r\sin\theta$.

Which package provides \theta?

None: \theta is built into LaTeX, so no extra package is required.

What is the most common mistake with theta in LaTeX?

Big-Theta notation uses the capital, \Theta(n log n); the lowercase \theta(n) is a function named theta.