Roman Numeral Converter

Convert between Roman numerals and decimal numbers. Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). The system uses subtractive notation where a smaller numeral before a larger one means subtraction: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. Roman numerals are still used today for clock faces, Super Bowl numbering, book chapters, movie sequels, and formal documents. The system has no zero and traditionally cannot represent fractions or very large numbers beyond 3,999. Understanding Roman numerals connects us to ancient history—the system was developed by the Romans around 500 BC and was the dominant number system in Europe for over a millennium.