Roman Numeral Converter

Convert numbers and Roman numerals

This converter turns any whole number from 1 to 3999 into Roman numerals, and any valid Roman numeral back into a number. It's handy for dates on buildings and film credits, book chapters, clock faces, monarch and event numbering (like Super Bowl LVIII), and homework.

Roman numerals use seven letters — I, V, X, L, C, D and M — combined with subtractive pairs like IV (4) and IX (9). The converter validates the input, so it flags a numeral that isn't properly formed.

Why the limit is 3999

Standard Roman numerals only run up to 3999 (MMMCMXCIX), because there's no standard single letter for 5000 or 10000. Larger numbers need a bar notation that isn't part of everyday use, so this tool keeps to the standard range.

Where you'll meet Roman numerals

Roman numerals turn up more often than you might expect: on analogue clock faces, in film and television copyright dates, on Super Bowl and Olympic Games numbering, in book chapters and volumes, on building cornerstones, and after the names of monarchs and popes (Elizabeth II, Louis XIV). Being able to convert both ways makes it easy to read a date carved above a doorway or to render a modern number in the classical style for a certificate or logo.

Related tools

Working with dates too? Find a date's weekday with the day of the week calculator, or its week number with the week number calculator.