Roman Numeral Converter
Numbers to Roman numerals and back — supports 1 to 3999.
About Roman Numeral Converter
Roman Numeral Converter goes both directions between Arabic numbers and Roman numerals. It is the right tool for chapter and section numbering (papers and books that use roman for prefatory pages), copyright dates on classic films, monarch and pope names (Henry VIII, John Paul II), and the occasional pub-quiz translation.
Worked example: 1989 converts to MCMLXXXIX (M for a thousand, then 'CM' for nine hundred — one hundred less than a thousand, then 'LXXX' for eighty, then 'IX' for nine — one less than ten). Going the other way, the same string decodes to 1989. Standard subtractive notation (IV for 4, IX for 9, XL for 40, XC for 90, CD for 400, CM for 900) is used, and malformed sequences (IIII, VV, IC) produce an error rather than silently returning a wrong number.
Two notes. The range is 1 to 3999, the conventional upper bound: classical Roman has no standard symbol above M, and while extended notations exist (overlines for thousand-multiples, M̄ for one million) they are not widely used. There is also no Roman numeral for zero — the concept did not exist in the system. For arithmetic, the practical approach is to convert to Arabic, do the math, and convert back; arithmetic directly in Roman is famously painful and was one of the practical drivers of Hindu-Arabic numeral adoption in medieval Europe.
Conversion runs in your browser.