Roman Numeral Converter

Where Roman numerals are used

Roman numerals appear on clock faces, book chapters and prefaces, movie sequels, monarchs’ names (Elizabeth II), sporting events, building foundation stones and copyright years in film credits. Students also meet them in school maths.

The symbols

The rules

• Symbols are written from largest to smallest and added: VIII = 5 + 1 + 1 + 1 = 8.
• A smaller symbol before a larger one is subtracted: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.
• Only I, X and C are used for subtraction, and only before the next two larger symbols.
• A symbol repeats at most three times: 4 is IV, not IIII.

This converter only accepts correctly formed numerals, so invalid forms like “IIII” or “VX” are flagged. That makes it useful for checking homework too.

Examples

1947 = MCMXLVII, 2026 = MMXXVI, 3999 = MMMCMXCIX (the largest standard Roman numeral). There is no zero in Roman numerals, and numbers above 3999 need special notation not covered here.

Related

To write numbers in words, use the number to words converter.

Examples

Quick answer

Why do some clocks show IIII instead of IV? It’s a traditional clockmakers’ style for visual balance, not standard notation.

Where students see them

In Indian schools, Roman numerals are taught in primary maths and used for class names (Class IX, X, XI, XII), chapter numbers and question sub-parts. Practising conversions both ways is a quick way to master the subtraction rule and the limits on repeating symbols. Try converting your birth year for practice: it is a fun way to remember the symbols.