Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers.
Standard numerals cover 1 to 3999. Roman input accepts the letters I, V, X, L, C, D and M.
How Roman numerals work
Roman numerals build numbers from seven letters, written largest to smallest and added together. The one twist is subtraction: a smaller symbol placed before a larger one is taken away rather than added.
| I V X L C D M | 1, 5, 10, 50, 100, 500, 1000 |
|---|---|
| Subtractive | IV=4, IX=9, XL=40, XC=90, CD=400, CM=900 |
No symbol repeats more than three times in a row, which is exactly why those six subtractive pairs exist — they avoid writing IIII or VIIII.
The year 2024 is written MMXXIV: two thousands (MM), twenty (XX) and four (IV, one before five). Standard Roman numerals run from 1 (I) to 3999 (MMMCMXCIX).
Still everywhere
Roman numerals linger on clock faces, in book chapters and film credits, on monuments and in the names of monarchs and sequels. Reading them is a small but genuinely useful literacy — and writing the year is a fun party trick.
Quick tips
- Left of larger means subtract. IX is 9, not 11.
- Max three in a row. Four of a kind triggers a subtractive pair instead.
- Work in chunks. Thousands, then hundreds, tens and units.