Roman Numeral Converter
Convert numbers to Roman numerals, and Roman numerals back to numbers.
What is the Roman Numeral Converter?
This tool converts a standard number into Roman numerals, or a Roman numeral back into a number, working in both directions live as you type.
How Roman numerals work
Roman numerals use seven letters as fixed values — I=1, V=5, X=10, L=50, C=100, D=500, M=1000 — combined by mostly adding values left to right (VI = 5+1 = 6), except when a smaller value appears before a larger one, which means subtract instead (IV = 5−1 = 4). This tool follows the standard modern convention used since the Middle Ages, which restricts subtractive pairs to specific combinations (IV, IX, XL, XC, CD, CM) rather than allowing arbitrary subtraction, matching how Roman numerals are used on clock faces, in book chapter numbering, and after monarchs' and popes' names today.
Why the range stops at 3999
Standard Roman numerals have no symbol for numbers at or above 4,000 without adding special notation (like a bar over a numeral to mean ×1,000), which historically varied and isn't in common modern use — so, like virtually every online Roman numeral tool, this one covers the standard 1-3999 range.
Want the "why" behind this tool? Read Why Roman Numerals Have No Symbol for Zero.