Expectation symbol (𝔼, E[X]) in LaTeX

Expectation symbol (𝔼, E[X])

Miscellaneous

𝔼

LaTeX command

\mathbb{E}[X]

blackboard E

Use inside math mode: $\mathbb{E}[X]$ — needs \usepackage{amssymb}

There is no single convention. Modern probability texts favour \mathbb{E}; statistics texts often use an upright E via \operatorname. The bracket style varies too: E[X], E(X) and E X all appear. Pick one and keep it.

All ways to write it

Command	Use	Package
`\mathbb{E}[X]`	blackboard E	amssymb
`\operatorname{E}[X]`	upright E	none
`E[X]`	plain italic E, common in older texts	none
`\mathrm{Var}(X)`	variance	none
`\operatorname{Cov}(X, Y)`	covariance	none
`\mathbb{P}(A)`	probability, same style	none

Commands marked with a package need that \usepackage line in a LaTeX document.

Example

\mathbb{E}[X] = \sum_{x} x \, P(X = x), \qquad \operatorname{Var}(X) = \mathbb{E}[X^2] - \mathbb{E}[X]^2

Expectation of a discrete variable and the variance identity.

Questions

How do I get a bold or upright E without amssymb?

\operatorname{E} gives an upright roman E in any setup, including KaTeX.

Related symbols

Real numbers ℝ \mathbb{R}
Summation ∑ \sum_{i=1}^{n}
Integral ∫ \int_{a}^{b} f(x)\,dx

Using expectation in Confluence

Confluence Cloud has no built-in LaTeX. With LaTeX Math for Confluence you add a math macro to any page, type \mathbb{E}[X] and it renders inline or as a block, with a live preview while you edit. Every command on this page renders there without extra packages.