HTMLRoman Numeral Converter
Convert integers to Roman numerals or Roman numerals back to integers. Supports 1–3,999. Shows standard notation (MCMXCIX) instantly as you type.
Ctrl+Enter to run | Ctrl+K to switch tools | Recent button shows input history
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What is the largest Roman numeral?
Traditional Roman numerals go up to 3,999 (MMMCMXCIX). Numbers above 3,999 require overlines or other extensions not in standard notation.
Why does IV equal 4?
Subtractive notation: a smaller numeral before a larger one means subtraction. IV = V(5) - I(1) = 4. This rule applies to IX, XL, XC, CD, CM as well.