Roman Numeral Converter

How do you read Roman numerals?

Roman numerals use seven symbols: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. The symbols are written side by side from largest to smallest and their values are added: VIII = 5 + 1 + 1 + 1 = 8, LXVI = 50 + 10 + 5 + 1 = 66.

When a smaller symbol stands to the left of a larger one it is subtracted. This happens in six pairs only: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400 and CM = 900.

How do you write a number in Roman numerals?

Split the number into thousands, hundreds, tens and ones, write each part on its own and join them. For 1994: 1000 = M, 900 = CM, 90 = XC, 4 = IV, which gives MCMXCIV. The year 2024 is MM + XX + IV = MMXXIV.

Rules

• I, X, C and M are repeated at most three times in a row: 3 = III, but 4 = IV.
• V, L and D are never repeated: 10 is X, not VV.
• Subtraction is used only in the six pairs above. 49 is XLIX, not IL, and 99 is XCIX, not IC.

If you type a numeral that breaks these rules, the tool tells you why and suggests the standard form.

Limits

The largest number that can be written this way is 3999 (MMMCMXCIX). Roman numerals have no zero, no negative numbers and no fractions. Larger numbers are written with a bar over a symbol to multiply it by a thousand, which this tool does not support.