U+2148\mathbb{i}ⅈ<mi>ⅈ</mi>Semantic identity and intent
Characters to distinguish
- ℂ — Complex Numbers
Use ⅈ in the right format
Meaning and usage
Can represent the imaginary unit in typographic systems that distinguish it from an ordinary variable i.
Use it only when the chosen style guide supports double-struck constants.
Pronunciation: double-struck italic i
Formula examples
i^2=-1How to type Double-Struck Italic i
- Windows
- Use Character Map and search for Double-Struck Italic i, or paste the Unicode character (U+2148).
- macOS
- Open Character Viewer with Control–Command–Space and search for Double-Struck Italic i.
- Microsoft Word
- In an equation, type \mathbb{i} and press Space when Word supports the command; otherwise insert the Unicode character.
- iPhone and iPad
- Copy and paste ⅈ, or use a math/LaTeX app. The standard iOS keyboard may not expose every mathematical symbol.
- Android
- Copy and paste ⅈ, or use a math keyboard or LaTeX editor. Keyboard layouts vary by device and app.
- Google Docs
- For plain text, paste ⅈ or use Insert → Special characters. For structured math, use the equation editor and verify \mathbb{i}.
- Excel
- Paste ⅈ into a cell or use Insert → Symbol when available. Ordinary cells preserve the character but do not interpret LaTeX commands.
Common mistakes
- Do not substitute a visually similar Latin or differently styled character for ⅈ; case and mathematical alphabet style can identify different quantities.
- For plain text, copy ⅈ as U+2148; for structured equations, use \mathbb{i} in math mode. A look-alike glyph or image can break search, accessibility, or parsing when the intended character is Double-Struck Italic i.
When to use ⅈ
- Use ⅈ in plain text when a Unicode character is appropriate and the destination preserves U+2148.
- Use \mathbb{i} in an equation editor when mathematical spacing or structure matters.
- Define the local meaning when Double-Struck Italic i is used in constants, math alphanumeric with a field-specific convention.
Look-alikes and related characters
- ℂ — Complex Numbers
Font and compatibility notes
Font coverage varies; verify the code point and destination rendering before publication.
Continue the workflow
From Double-Struck Italic i to a finished equation
- Copy the characterUse ⅈ in plain text when Unicode is accepted.
- Choose a structured formatUse
\mathbb{i}for 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 Double-Struck Italic i symbol mean?
Can represent the imaginary unit in typographic systems that distinguish it from an ordinary variable i.
What is the LaTeX command for ⅈ?
Use \mathbb{i} in a compatible math environment.
Can I copy ⅈ as Unicode?
Yes. Use the copy button above to copy the Unicode character directly.