Roman Numerals Converter
Convert any number between 1 and 3999 to or from Roman numerals. Strict validation rejects invalid forms.
Roman Numerals
Convert any year (1–3999) to and from Roman numerals.
About the Roman Numerals Converter
Enter a number to get the Roman numeral form, or enter Roman numerals to get the numeric value. The converter validates strictly — only canonical forms (I, IV, V, IX, X, XL, L, XC, C, CD, D, CM, M) are accepted.
Standard Roman numerals only go up to 3999 (MMMCMXCIX). For higher numbers, additional notation is needed.
How it works
Roman → Arabic: scan left to right; if a numeral is smaller than the next one, subtract; otherwise add. The calculator validates strictly — only canonical forms (IV not IIII, IX not VIIII) are accepted. Arabic → Roman: greedy match against the symbol list M, CM, D, CD, C, XC, L, XL, X, IX, V, IV, I, repeating until exhausted.
Examples
- 2026MMXXVI
- MCMLIV1954
- 49XLIX