U+2160 · Letter number
Roman Numeral One Symbol Ⅰ
Ⅰ is roman numeral one, U+2160. Unicode records it as a compatibility form of I (compat form). It was added in Unicode 1.1, and Unicode files it under Letter number.
Codes & technical data
| Unicode | U+2160 | |
|---|---|---|
| HTML hex | Ⅰ | |
| HTML decimal | Ⅰ | |
| CSS | \2160 | |
| JavaScript | \u{2160} | |
| Python | \U00002160 | |
| Java / C# | \u2160 | |
| Rust | \u{2160} | |
| Swift | \u{2160} | |
| PHP | \u{2160} | |
| URL encoded | %E2%85%A0 | |
| UTF-8 bytes | E2 85 A0 | |
| UTF-16 bytes | 2160 | |
| Base64 | 4oWg | |
| Decimal | 8544 | |
| Decomposes to | I (compat form) | |
| Numeric value | 1 | |
| Category | Letter number (Nl) | |
| Introduced | Unicode 1.1 | |
Will Ⅰ survive being pasted?
- Normalisation. No. Anything that applies NFKC — search indexes, usernames, domain names, programming identifiers — rewrites Ⅰ as
I. Safe for display, not for storage. - Legacy encodings. Ⅰ is Unicode-only — it has no Latin-1 equivalent, so a system stuck on an 8-bit encoding cannot represent it.
- Size. 3 bytes in UTF-8. Character-limited fields — SMS, bios, some form validators — usually count bytes, not characters.
Other one characters
Unicode names 10 characters ending in “one”. They differ by direction, weight or decoration rather than by meaning.
Nearby in Number Forms
Roman numerals as single characters, and the vulgar fractions beyond the three Latin-1 supplies. A Roman numeral here is one character, not a run of letters, so Ⅷ and VIII sort and search differently.
How to type Ⅰ
| Windows | Type 2160 then press Alt+X |
|---|---|
| macOS | Press Ctrl+Cmd+Space, then search for “roman numeral one” |
| Linux | Press Ctrl+Shift+U, type 2160, press Enter |
| HTML | Ⅰ |
About Unicode’s Letter number category
This is a letter number: a character that looks like a letter but carries a numeric value, the way Roman numerals do.
Frequently asked questions
- How do I type the Ⅰ roman numeral one symbol?
- On Windows, type 2160 and press Alt+X. On Linux press Ctrl+Shift+U then 2160. On any system the quickest route is the copy button on this page.
- What is the code for Ⅰ?
- Roman Numeral One is U+2160. In UTF-8 it takes 3 bytes. The table above lists every escape format.
- Will Ⅰ survive being pasted anywhere?
- Not always. Roman Numeral One is a compatibility character: any system that applies Unicode NFKC normalisation — search indexes, usernames, identifiers — replaces it with I. Use it for display, not where text is normalised.