How do Roman numerals work?

Letters stand for values: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. They are added left to right, except when a smaller value precedes a larger one (IV=4, IX=9, XL=40), which means subtraction.

What is the largest Roman numeral?

In standard notation the largest is MMMCMXCIX = 3999. There is no symbol for zero, and 4000+ requires non-standard overline notation, so this tool covers 1–3999.

Why is 4 written IV and not IIII?

Standard notation uses subtraction to avoid four repeated symbols, so 4 is IV (one before five). Clock faces sometimes use IIII for aesthetic balance, but IV is the canonical form.

Roman Numeral Converter

Free Roman numeral converter. Turn any number from 1 to 3999 into Roman numerals, or decode a Roman numeral back to a regular number. Uses standard subtractive notation (IV, IX, XL…).

Convert numbers to Roman numerals and Roman numerals back to numbers (1–3999).

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