Roman Numeral Converter
Convert between numbers and Roman numerals both ways.
Frequently Asked Questions
What are the subtractive rules in Roman numerals?
A smaller symbol before a larger one subtracts: IV is 4, IX is 9, XL is 40 and CM is 900. Only I, X and C are used subtractively, and each pairs only with the next two larger symbols.
Why does the system stop at 3999?
Standard notation never repeats a symbol more than three times, so the largest value is MMMCMXCIX (3999). Larger numbers historically used a bar over a numeral to multiply it by 1,000.
Where are Roman numerals still used?
Clock faces, book chapters, film and game sequels, sporting events like the Olympics and Super Bowl, monarch names, and outlines or legal documents where a classic style is wanted.
Is the Roman Numeral Converter free, and is my data private?
Yes. It is completely free and every calculation runs locally in your browser, so the numbers and dates you enter are never uploaded, stored, or shared with anyone.
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