Roman Numeral Converter
Enter any integer from 1 to 3999 to get the Roman numeral — or type a Roman numeral to decode it back to a number.
Basic Symbols
Subtractive Notation
When a smaller symbol appears before a larger one, it is subtracted. This avoids repeating a symbol more than three times.
How Roman numerals work
Roman numerals use seven letters — I (1), V (5), X (10), L (50), C (100), D (500), and M (1 000). Numbers are built by combining these symbols from largest to smallest, reading left to right. For example, VIII = 5 + 1 + 1 + 1 = 8, and MMXXIV = 1 000 + 1 000 + 10 + 10 + 5 − 1 = 2 024.
The key rule is subtractive notation: a smaller symbol placed before a larger one is subtracted rather than added. This keeps numerals compact and avoids repeating a symbol more than three times. The six subtractive pairs are: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900).
Why only 1–3999?
The standard Roman numeral system has no symbol larger than M (1 000), so the highest number expressible without special overline notation is 3 999 — written as MMMCMXCIX. The number 4 000 would require four Ms in a row, which breaks the three-repetition rule. Ancient Romans sometimes used a bar over a numeral to multiply it by 1 000, but this is not universally supported in digital typography, so most converters cap at 3 999.
Common uses of Roman numerals today
- Clock and watch faces (IV or IIII for 4)
- Chapter and section numbering in books
- Movie and TV sequel titles (Rocky IV, Star Wars Episode IX)
- Olympic Games and Super Bowl editions (Super Bowl LVIII)
- Monuments, buildings, and copyright years
- Outline levels in academic and legal documents
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