Alpha in LaTeX (\alpha)

Where it is used

Lowercase Greek alpha, a default name for angles, significance levels, learning rates, and coefficients.

In statistics \alpha is the significance level of a test, as in \alpha = 0.05, and the shape parameter of the Beta and Gamma distributions. Physicists use it for the fine-structure constant \alpha \approx 1/137 and for alpha particles. Geometry assigns it to angles, often alongside \beta and \gamma. There is no capital \Alpha command, because capital alpha is identical to the Latin A; write A or \mathrm{A}. Take care that \alpha and the Latin a, or the proportional sign \propto, are not confused in handwriting-style fonts.

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\usepackage{amsmath}
\begin{document}
Alpha: $\alpha$

\[ P(\text{reject } H_0 \mid H_0 \text{ true}) = \alpha \]
\end{document}

Related symbols

• Beta\beta
• Gamma\gamma
• Gamma (Upper)\Gamma
• Delta\delta
• Delta (Upper)\Delta
• Epsilon\epsilon

Frequently asked questions

How do I write Alpha in LaTeX?

Type \alpha in math mode, for example $P(\text{reject } H_0 \mid H_0 \text{ true}) = \alpha$. It works in plain LaTeX without loading any package.

Which package do I need for \alpha?

None. \alpha is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \alpha in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\alpha$ in running text. If you only need the glyph in text, paste the Unicode character α instead (with XeLaTeX or LuaLaTeX and a font that has it).