Roman Numeral Converter

How to use

1. 1Enter a number from 1 to 3999 on the left (e.g. 2026 → MMXXVI).
2. 2Enter Roman numerals on the right (e.g. MCMXCIV → 1994); invalid input shows why.
3. 3Turn on the overline (vinculum) option for numbers above 3999.
4. 4Click a year example or open the chart for the basic values.

How Roman numerals work

There are seven symbols: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. Symbols are written from largest to smallest and added (XVI = 10 + 5 + 1 = 16). A smaller symbol placed before a larger one is subtracted: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. So 1994 = M + CM + XC + IV = MCMXCIV. The converter shows this breakdown for every result.

Rules and common mistakes

I, X, C and M may repeat at most three times in a row (4 is IV, not IIII). V, L and D are never repeated and never subtracted (95 is XCV, not VC). Only I can precede V and X, only X can precede L and C, and only C can precede D and M (99 is XCIX, not IC). Enter a numeral that breaks a rule and the tool tells you which rule and what the correct form is. The IIII seen on many clock faces is a traditional exception.

Years, regnal numbers and chapters

Roman numerals are still used for years (film copyright dates such as MCMXCIX), monarchs and popes (Elizabeth II, Louis XIV), Super Bowls, book chapters and volumes, clock faces and tattoos. The standard system stops at 3999 (MMMCMXCIX); larger values put a bar over a letter to multiply it by 1,000 (V̅ = 5,000). There is no Roman numeral for zero or negative numbers.

Frequently asked questions

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