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Ⅻ Roman Numeral Converter
Roman numerals use letters from the Latin alphabet — I, V, X, L, C, D, M — to represent numbers. This converter handles values from 1 to 3999 in both directions, with validation for malformed Roman numeral strings.
Examples
2026MMXXVI4IVSubtractive notation — 4 is IV (5 − 1), not IIII.
1999MCMXCIXFrequently asked questions
Why no Roman numerals over 3999?
Standard Roman numerals max out at MMMCMXCIX (3999). Larger numbers use a bar over the letter to multiply by 1000, which is not commonly typeable.
Why is 4 written IV not IIII?
Subtractive notation: place a smaller numeral before a larger one to subtract. IV = 5−1 = 4. (Clock faces often break this rule and use IIII for visual balance.)
Is there a Roman zero?
No. Romans had no symbol for zero. Medieval scholars sometimes used N (for nulla / nihil).
About this tool
Roman Numeral Converter runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.
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Why this tool
vs typical free web-tool sites
| 1vw | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for premium features) |
| Ads inside the tool | No | Yes (banner + video) |
| Data sent to server | No (browser-only) | Yes (inputs analyzed for ads) |
| Total tools | 96 | Often <20 or scattered across sites |
| Bookmarkable URL per tool | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Open source | Yes | No |