UnicodeCharactercom
𝕀
U+1D540 Β· MATHEMATICAL DOUBLE-STRUCK CAPITAL I

Mathematical Double-Struck Capital I

  • CodepointU+1D540
  • NameMATHEMATICAL DOUBLE-STRUCK CAPITAL I
  • Decimal120128
  • BlockMathematical Alphanumeric Symbols (U+1D400–U+1D7FF)
  • Plane1 β€” Supplementary Multilingual Plane
  • ScriptCommon
  • CategoryLu β€” Uppercase Letter
  • Unicode version3.1 (2001)
  • Bidi classL β€” Left-to-Right
  • Combining class0
  • East Asian widthN β€” Neutral
  • MirroredNo

About this character

U+1D540 (𝕀) is MATHEMATICAL DOUBLE-STRUCK CAPITAL I, an uppercase letter in the Mathematical Alphanumeric Symbols block. Its script is Common: it is shared by many writing systems rather than belonging to one. It was added in Unicode 3.1 (2001).

It is a font variant of U+0049 I (compatibility decomposition <font>). NFC and NFD leave it alone, but NFKC and NFKD replace it with U+0049 I. Search engines, identifier checks and username systems that apply NFKC will treat the two as the same text.

How to type 𝕀

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Encodings & escapes

UTF-8 encoder β†’
UTF-8F0 9D 95 804 bytes
UTF-16D835 DD40surrogate pair
UTF-320001D5404 bytes
HTML named&Iopf;named character reference
HTML decimal&#120128;
HTML hex&#x1D540;
CSS\1D540in content: "…"
JavaScript\u{1D540}ES2015+
JavaScript\uD835\uDD40surrogate pair
JSON\uD835\uDD40
Python\U0001D540
Python\N{MATHEMATICAL DOUBLE-STRUCK CAPITAL I}by name
Java / C#\uD835\uDD40
C / C++\U0001D540universal character name
Rust / Swift / PHP\u{1D540}
Go\U0001D540
Ruby\u{1D540}
Excel / Sheets=UNICHAR(120128)
URL-encoded%F0%9D%95%80percent-encoded UTF-8
Β§

Normalization forms

Normalizer β†’
NFCunchanged
NFDunchanged
NFKCU+0049 I
NFKDU+0049 I
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Looks similar

Characters that Unicode’s security data (UTS #39 confusables) lists as visually confusable with this one. Useful for spotting lookalike spoofing in URLs and usernames.

U+00311Digit One U+0049ILatin Capital Letter I U+006ClLatin Small Letter L U+007C|Vertical Line U+0196Ζ–Latin Capital Letter Iota U+01C0Η€Latin Letter Dental Click U+0399Ξ™Greek Capital Letter Iota U+0406Π†Cyrillic Capital Letter Byelorussian-Ukrainian I U+04C0Σ€Cyrillic Letter Palochka U+05C0Χ€Hebrew Punctuation Paseq U+05D5Χ•Hebrew Letter Vav U+05DFןHebrew Letter Final Nun U+0627Ψ§Arabic Letter Alef U+0661Ω‘Arabic-Indic Digit One U+06F1Ϋ±Extended Arabic-Indic Digit One U+16C1ᛁRunic Letter Isaz Is Iss I
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Nearby in Mathematical Alphanumeric Symbols

All in block β†’
U+1D53B𝔻Mathematical Double-Struck Capital D U+1D53C𝔼Mathematical Double-Struck Capital E U+1D53D𝔽Mathematical Double-Struck Capital F U+1D53E𝔾Mathematical Double-Struck Capital G U+1D541𝕁Mathematical Double-Struck Capital J U+1D542𝕂Mathematical Double-Struck Capital K U+1D543𝕃Mathematical Double-Struck Capital L U+1D544𝕄Mathematical Double-Struck Capital M U+1D546𝕆Mathematical Double-Struck Capital O