Roman numeral converter
Convert Arabic numbers to Roman numerals and back.
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About the roman numeral converter
Converts in whichever direction you need: type digits and get Roman numerals, type numerals and get a number back. Input is validated against subtractive notation, so a malformed string like IIX is rejected rather than silently guessed at.
Frequently asked questions
Why does it stop at 3999?
Standard notation has no symbol above M for a thousand. Larger values need a vinculum — an overbar meaning "multiply by a thousand" — which has no single agreed plain-text representation.
Is IIII or IV correct for four?
IV is the standard subtractive form and what this tool produces. IIII survives on clock faces for visual balance, but it is not accepted in normal use.