Convert between Arabic numbers and Roman numerals instantly
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Free online Roman numeral converter. Convert Arabic numbers (1–3999) to Roman numerals and back. Supports all standard Roman numeral rules including subtractive notation.
Roman numerals are a numeric system originating in ancient Rome that uses letters: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000).
When a smaller numeral precedes a larger one, it is subtracted. For example, IV = 4 (5-1) and IX = 9 (10-1). This rule applies to I before V and X, X before L and C, and C before D and M.
The standard system goes up to 3999 (MMMCMXCIX). Numbers above 3999 require a bar (vinculum) over a numeral to multiply it by 1000, which is non-standard.
Roman numerals appear in clock faces, book chapter numbering, movie sequel titles, Super Bowl names, and copyright years. They convey a formal or classic aesthetic.
MM = 2000, XX = 20, V = 5. So MMXXV = 2025.
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Last updated: January 2025