Roman Numeral Converter
Precision conversion between modern Arabic numbers and ancient Roman symbols.
"Two thousand twenty four"
Basic Symbols
Famous Years
Roman Numeral Rules
- 01
Values are added when a smaller or equal symbol follows a larger one (e.g., VI = 5 + 1 = 6).
- 02
A smaller symbol before a larger one is subtracted (e.g., IV = 5 - 1 = 4). This only applies to specific pairs like IV, IX, XL, XC, CD, CM.
- 03
Symbols cannot be repeated more than three times in a row. For example, 4 is IV, not IIII.
Frequently Asked Questions
Roman Numerals: Reading the Old System Fluently
The system in one table
Seven symbols and one subtraction rule generate everything:
| Symbol | Value | Subtractive pairs |
|---|---|---|
| I / V / X | 1 / 5 / 10 | IV = 4, IX = 9 |
| L / C | 50 / 100 | XL = 40, XC = 90 |
| D / M | 500 / 1000 | CD = 400, CM = 900 |
| Example | 2026 | MMXXVI |
| Example | 1947 | MCMXLVII |
The rules people trip on
Only I, X and C subtract, and only from the next two steps up — IV works, IC (99) does not; 99 is XCIX. No symbol repeats more than three times: 40 is XL, never XXXX. And there's no zero at all, which is half the reason the system lost to Arabic numerals for arithmetic. Conversion errors cluster exactly at these rules — 49, 99, 444, 999 are the classic test cases (XLIX, XCIX, CDXLIV, CMXCIX).
Where you still need them
Clock faces, book prefaces and chapter numbers, movie sequels and copyright years (MMXXVI in the credits), outline numbering, monument inscriptions — and exam questions. For numbers in words (cheques, legal documents), the number to words converter is the right tool; for other numeral systems entirely, the base converter.