Roman Numeral Converter
Type a number or a Roman numeral and the converter works out which way to go.
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The formula
Add the values of the symbols, except when a smaller symbol sits before a larger one: then subtract it (IV = 4, IX = 9, XC = 90).
The seven symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
The rules
- Symbols are written largest to smallest and added: XVI = 10 + 5 + 1 = 16.
- A symbol is never repeated more than three times in a row, so 4 is IV, not IIII.
- Only I, X and C can be subtracted, and only from the next two bigger symbols: IV, IX, XL, XC, CD, CM.
- There is no zero and no standard way to write numbers above 3,999.
Examples
1994 is MCMXCIV (1000 + 900 + 90 + 4). 2026 is MMXXVI (2000 + 20 + 6). 49 is XLIX, which is XL (40) plus IX (9), not IL.
Where you still see them
Clock faces, film and TV copyright years, book chapters and prefaces, Super Bowl numbering and monarchs such as Elizabeth II.
Examples to check
Type these into the calculator above to see how it behaves. Every result below was produced by the same calculator code that runs on this page.
| What you enter | What you get |
|---|---|
| Number (1 to 3999) or Roman numeral: 2026 | Roman numeral: MMXXVI |
| Number (1 to 3999) or Roman numeral: 1994 | Roman numeral: MCMXCIV |
| Number (1 to 3999) or Roman numeral: XLIX | Number: 49 |
| Number (1 to 3999) or Roman numeral: MMXXV | Number: 2,025 |
Roman Numeral Converter: frequently asked questions
Why does the converter reject IIII or IC?
Those are not standard forms. Clock faces sometimes use IIII as a style choice, but the standard rules require IV. IC is not allowed because I can only be subtracted from V and X.
How do I write a number above 3,999?
In classical Roman numerals you do not. A bar over a numeral multiplies it by 1,000, but that is outside the standard form this tool supports.
How accurate is this calculator?
It uses standard double-precision arithmetic, accurate to about 15 significant digits. Results are rounded only for display.
Is what I enter in this calculator saved or sent anywhere?
No. The calculation runs in your browser, so what you enter is not sent to our servers. We only count, anonymously, whether a tool ran successfully.
Is this calculator free to use?
Yes. It is free, needs no sign-up and has no usage limit.
Last reviewed: October 3, 2026