U+004FOOO<mo>O</mo>Semantic identity and intent
Characters to distinguish
- o — Little O
- xₖ — Iteration Value x Sub k
- ∎ — End of Proof
Use O in the right format
Meaning and usage
Represents Big O asymptotic notation for describing growth, error, or limiting behavior.
State the limiting variable and comparison function; asymptotic notation is incomplete without its context.
Pronunciation: big o
Formula examples
O is used in a context where represents Big O asymptotic notation for describing growth, error, or limiting behavior.How to type Big O
- Windows
- Use Character Map or enter U+004F in a Unicode-aware application.
- macOS
- Open Character Viewer with Control–Command–Space and search by the symbol name.
- Microsoft Word
- In an equation, type O and press Space when Word supports the command.
- iPhone and iPad
- Copy and paste O, or use a math/LaTeX app. The standard iOS keyboard may not expose every mathematical symbol.
- Android
- Copy and paste O, or use a math keyboard or LaTeX editor. Keyboard layouts vary by device and app.
- Google Docs
- For plain text, paste O or use Insert → Special characters. For structured math, use the equation editor and verify O.
- Excel
- Paste O into a cell or use Insert → Symbol when available. Ordinary cells preserve the character but do not interpret LaTeX commands.
Common mistakes
- Confirm the field-specific convention before using O; State the limiting variable and comparison function; asymptotic notation is incomplete without its context.
- For plain text, copy O as U+004F; for structured equations, use O in math mode. A look-alike glyph or image can break search, accessibility, or parsing when the intended character is Big O.
When to use O
- Use O in plain text when a Unicode character is appropriate and the destination preserves U+004F.
- Use O in an equation editor when mathematical spacing or structure matters.
- Define the local meaning when Big O is used in numerical methods, discrete math with a field-specific convention.
Look-alikes and related characters
- o — Little O
- xₖ — Iteration Value x Sub k
- ∎ — End of Proof
Font and compatibility notes
Font coverage varies; verify the code point and destination rendering before publication.
Continue the workflow
From Big O to a finished equation
- Copy the characterUse O in plain text when Unicode is accepted.
- Choose a structured formatUse
Ofor LaTeX or the MathML snippet for accessible web equations. - Edit or convertOpen the value in the editor or converter without retyping it.
Review and source notes
Quality tier: catalog
Last reviewed: 2026-07-23
Review method: Catalog review of character identity and notation mappings.
Verified against: Unicode Standard, Unicode mathematical notation guidance, and established LaTeX/MathML syntax.
Reference sources
- The Unicode StandardUnicode Consortium — Character identity, encoding, names, and conformance.
- Unicode Character Code ChartsUnicode Consortium — Code points and official character charts.
Frequently asked questions
What does the Big O symbol mean?
Represents Big O asymptotic notation for describing growth, error, or limiting behavior.
What is the LaTeX command for O?
Use O in a compatible math environment.
Can I copy O as Unicode?
Yes. Use the copy button above to copy the Unicode character directly.