Roman numerals have been used for over 2,000 years and remain ubiquitous today — on clock faces, movie credits, book chapters, Super Bowl numbering, and building cornerstones. This converter translates between Roman numerals and decimal numbers instantly, showing the step-by-step breakdown of how subtractive notation works (e.g., IV = 5 − 1 = 4).
How to Use the Converter
The converter works both ways:
- Roman → Decimal: Type Roman numerals (e.g., MCMXCIV) to see the decimal value (1994)
- Decimal → Roman: Type a number (e.g., 2024) to see the Roman form (MMXXIV)
- Step-by-step: See how each symbol contributes to the total
Roman Numeral Rules
Seven symbols form the basis: I (1), V (5), X (10), L (50), C (100), D (500), M (1000).
Additive rule: Symbols are generally added left to right: XVIII = 10 + 5 + 1 + 1 + 1 = 18.
Subtractive rule: A smaller symbol before a larger one means subtraction: IV = 5 − 1 = 4, XC = 100 − 10 = 90.
Only I, X, and C can be used subtractively, and only before the next two larger symbols.
Modern Uses of Roman Numerals
- Clock faces: Most use IIII instead of IV (watchmaker's tradition)
- Movie/game sequels: Rocky II, Final Fantasy VII, Star Wars Episode IV
- Super Bowl: Super Bowl LVIII (58)
- Monarchs & popes: Queen Elizabeth II, Pope Benedict XVI
- Copyright years: © MMXXIV at the end of movie credits
Step-by-Step Instructions
- 1Choose the conversion direction: Roman → Decimal or Decimal → Roman.
- 2Enter a Roman numeral (e.g., MCMXCIV) or a decimal number (e.g., 1994).
- 3View the instant conversion result.
- 4Study the step-by-step breakdown showing how each symbol is processed.
- 5Use the reference chart below for quick lookups.