Roman Numerals ⇄ Integer
Convert both ways (1–3999) with format validation.
Last updated: 2025-09-05
Rules: I, V, X, L, C, D, M. I before V/X; X before L/C; C before D/M.
Standard form up to 3,999 is supported.
How to use
- Enter an integer (1–3999) or a Roman numeral string.
- The tool converts in the other direction automatically.
- Invalid input is flagged; use standard forms (e.g. IV not IIII).
Examples
- 1999 → MCMXCIX
- XLIV → 44
FAQ
- What range is supported?
- Standard Roman numerals from 1 to 3,999.
- Why invalid?
- We enforce standard forms (e.g., IV not IIII).
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Informational only; verify critical results independently.