Little-o in LaTeX

The LaTeX command for little o (o) is o (little-o (strict upper bound)).

o

Computer Science · Unicode o (U+006F) · no package needed

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Which command should you use?

Command	Package	Use it when
`o(n)` recommended	none	Little-o is simply the letter o.
`O(n \log n)`	none	Big-O.
`\mathcal{O}(n)`	none	Calligraphic big-O, a common style.
`\Theta(n)`	none	Theta, the tight bound.

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

Common mistake. Do not use \circ (a ring operator) for little-o, and \mathcal{o} does not exist: calligraphic letters are capitals only.

How to type Little-o

Write o 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

$f(n) = o(g(n))$

f(n) = o(g(n))

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Related Computer Science symbols

\bot\models\mathsf{NP}\mathsf{P}\mathcal{O}\Omega\Theta\oplus\land\lor\neg\mid\lfloor x \rfloor\lceil x \rceil

Computer science symbols in LaTeX: the full table or search all 350+ LaTeX symbols.

FAQ

How do you write little o (o) in LaTeX?

Use o in math mode; it needs no extra package. For example, $f(n) = o(g(n))$.

Which package provides o?

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

What is the most common mistake with little o in LaTeX?

Do not use \circ (a ring operator) for little-o, and \mathcal{o} does not exist: calligraphic letters are capitals only.