Roman Numeral Converter

Convert between Roman numerals and decimal numbers instantly. Supports 1 to 3,999,999 with full validation, batch mode, and a complete reference table.

Decimal → Roman
Decimal Number (1 – 3,999,999)
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Roman → Decimal
Roman Numeral
Enter Roman numerals above
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Roman numeral rules

Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), M (1000). Symbols are generally written largest to smallest from left to right.

Subtractive notation: IV = 4 (not IIII), IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. Only one small-value symbol may precede a larger one.

The standard system goes up to 3,999 (MMMCMXCIX). For larger numbers, a bar over a numeral (vinculum) multiplies it by 1,000 — this tool represents those with parentheses notation.