Uppercase C Double Struck (ℂ) is the Unicode character at U+2102 (DOUBLE-STRUCK CAPITAL C) in Letterlike Symbols. It is the blackboard-bold capital C commonly used for the set of complex numbers.
Remember
Character ℂ
Unicode U+2102
Hex entity ℂ
Decimal ℂ
Named ℂ ℂ
CSS escape \2102
Official name DOUBLE-STRUCK CAPITAL C
All of these produce the same glyph: ℂ. Compare with ordinary Uppercase C (U+0043).
Using Hex Code: ℂ
Using HTML Code: ℂ
Using Named Entity: ℂ
Using CSS Entity: ℂ
z ∈ ℂ
How It Works
1. Hex / decimal:U+2102 → ℂ or ℂ in HTML.
2. Named:ℂ and ℂ are HTML5 aliases for the same code point.
3. CSS: use \2102 in content (not an HTML entity). #point::after appends that glyph after the paragraph text.
4. Math sample:∈ is ∈; together with ℂ it shows “z belongs to ℂ”.
Pitfalls & Tips
Common mistakes when working with this character.
Named
Two names, one glyph
ℂ and ℂ are aliases. Prefer ℂ when meaning the complex set; ℂ is shorter.
Look-alikes
Not ordinary C
U+2102 is double-struck. U+0043 is ordinary C. A bold font on plain C is not the same character.
Fonts
Check math font coverage
Some fonts omit U+2102 or render a fallback. Prefer fonts with Letterlike / math support (for example Cambria Math).
A11y
Explain math symbols
Screen readers may not name double-struck letters clearly. Add plain-language context such as “complex numbers” nearby.
CSS vs HTML
Do not mix escapes
\2102 belongs in CSS. Named/numeric entities belong in HTML.
Semicolon
End references
Always finish with ; — write ℂ, not &Copf.
Compatibility
Browser Support
Uppercase C Double Struck / DOUBLE-STRUCK CAPITAL C (U+2102) and its entity forms (ℂ, ℂ, ℂ, ℂ, CSS \\2102) are supported in all mainstream browsers. Glyph shape depends on the font.
✓ Universal support
Uppercase C Double Struck
Encode with named, hex, decimal, or CSS escape — or paste the character in UTF-8 HTML.
100%Browser coverage
Google ChromeSupported
Yes
Microsoft EdgeSupported
Yes
Mozilla FirefoxSupported
Yes
Apple SafariSupported
Yes
OperaSupported
Yes
Internet ExplorerAll versions
Yes
U+2102 / entitiesFull support
Bottom line: Prefer ℂ or ℂ for readable markup; use \\2102 only inside CSS content.
Remember
Key Takeaways
Unicode: this character is U+2102 (decimal 8450) — DOUBLE-STRUCK CAPITAL C.
HTML: prefer ℂ / ℂ, or use ℂ / ℂ.
CSS: use \2102 inside content for generated text.
Watch out: U+2102 ≠ U+0043; font styling alone is not enough.
One line:U+2102 → ℂ / ℂ / CSS \2102.
Frequently Asked Questions
Use ℂ or ℂ (named), ℂ (hex), ℂ (decimal), or the CSS escape \2102 in the content property. All render U+2102.
U+2102 (hex 2102, decimal 8450). Unicode names it DOUBLE-STRUCK CAPITAL C. It belongs to Letterlike Symbols and commonly denotes the set of complex numbers.
Yes. HTML5 defines ℂ and ℂ — both map to U+2102.
U+2102 is a double-struck (blackboard bold) capital C used in math. U+0043 is ordinary capital C. They look different and serve different roles.
HTML entities (ℂ, ℂ, or ℂ) go in markup. The CSS escape \2102 is used in stylesheets (usually in the content property of ::before/::after). Both render the same glyph.
Use it in mathematical text for the complex numbers set (ℂ), set theory, or other double-struck notation. Prefer ℂ or ℂ for readable markup.
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Did you know?
This character is Unicode U+2102 (decimal 8450) — official name DOUBLE-STRUCK CAPITAL C in Letterlike Symbols. HTML5 defines ℂ and ℂ. In mathematics it commonly denotes the set of complex numbers ℂ.
