Alpha (α) in LaTeX
\alpha typesets the lowercase Greek letter alpha (α) in maths mode; there is no separate LaTeX command for a capital alpha because it is visually identical to a plain Latin A, so authors just type A.
LaTeX command
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Alpha is one of the most overloaded symbols in mathematics, statistics and physics: it commonly denotes an angle in geometry and trigonometry, a significance level in a hypothesis test (typically 0.05), a learning rate or regularisation constant in statistics and machine learning, and the fine-structure constant in physics.
Because uppercase alpha looks exactly like a Roman A, LaTeX has no \Alpha command; if a document needs an uppercase alpha it is simply typed as A. This holds for several Greek letters whose capitals coincide with Latin letters, beta's capital is B, and so on.
In statistics, keep alpha as the significance level (a fixed threshold like 0.05, the probability of a Type I error) distinct from Cronbach's alpha, a reliability coefficient; both are common in the same field but mean very different things, so state which one you mean on first use.
Other forms
\alphalowercase alphaExamples
$\alpha$lowercase alpha inline
$\alpha = 0.05$the significance level in a hypothesis test
$\sin\alpha$alpha used as an angle
$y = \alpha + \beta x$alpha as a regression intercept
$\alpha \in (0, 1)$alpha as a smoothing or mixing parameter
Tips and common mistakes
- There is no
\Alphacommand, an uppercase alpha is just a plain A, since the glyphs are identical. - Don't confuse the statistical significance level alpha with Cronbach's alpha, a reliability coefficient, state which one you mean on first use.
- In physics,
\alphais the standard symbol for angular acceleration and also for the dimensionless fine-structure constant, surrounding units usually disambiguate which. \alphaneeds no extra package, it is part of core LaTeX maths.- For a bold alpha in a vector or tensor context, use
\boldsymbol{\alpha}rather than\mathbf{\alpha}, which does not bold lowercase Greek letters.
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Convert your maths to LaTeX →FAQ
What is the LaTeX command for alpha?
\alpha, used directly inside maths mode, for example .
How do I type a capital alpha in LaTeX?
You don't need a special command, just type an ordinary A, since capital alpha is visually identical to the Latin letter A.
What does alpha mean in statistics?
Most often the significance level of a hypothesis test, commonly set to 0.05, though it can also refer to Cronbach's alpha, a measure of internal reliability, check the surrounding context.
Is there a variant form of alpha, like \varepsilon for epsilon?
No, alpha has only the one standard form, \alpha; it does not have a var- variant the way epsilon, phi, theta and a few others do.