Roman Numeral Converter

Convert any number (1–3999) to Roman numerals, or translate a Roman numeral back to a number — instantly.

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Enter your values and click Calculate

Roman numerals use seven letters — I, V, X, L, C, D, and M — to represent values of 1, 5, 10, 50, 100, 500, and 1000. Numbers are formed by combining these symbols, with smaller values subtracted when they appear before larger ones (subtractive notation). For example, IV means 4 (5 minus 1) and IX means 9 (10 minus 1). This system handles all integers from 1 to 3999. The number 4000 and above cannot be expressed in standard Roman notation without extended conventions. Roman numerals remain in use today for clock faces, book chapter headings, film sequel numbering, copyright years, and formal document outlines. This converter works in both directions: enter a number to get its Roman numeral equivalent, or toggle reverse mode to translate a Roman numeral back to a standard integer.

How It Works

To convert a number to Roman numerals, the algorithm works from the largest value (M = 1000) down to the smallest (I = 1). At each step it subtracts the largest possible value and appends the corresponding symbol, repeating until nothing remains. For example, 1994: subtract 1000 (M), then 900 (CM), then 90 (XC), then 4 (IV), yielding MCMXCIV. The subtractive pairs — IV, IX, XL, XC, CD, CM — exist to avoid four consecutive identical symbols and make numbers more readable. To convert Roman numerals back to a number, each character is mapped to its value. If a character's value is less than the next character's value, it is subtracted; otherwise it is added. For example, XIV: X(10) + I(1 < V, so subtract) + V(5) = 10 − 1 + 5 = 14. The converter validates results by round-tripping: the input Roman numeral must exactly match what the converter produces for that number, which catches non-standard or malformed strings like IIX.

Examples

Current Year
Converting 2024 to its Roman numeral representation.
Result: 2024 = MMXXIV.
Super Bowl Number
Converting 58 — the number of Super Bowl LVIII.
Result: 58 = LVIII.
Reverse: MCMXCIX
Translating the Roman numeral MCMXCIX back to a number.
Result: MCMXCIX = 1999.

Frequently Asked Questions

Why does Roman notation stop at 3999?
Standard Roman numerals can represent up to 3999 (MMMCMXCIX). To represent 4000, you would need four M's in a row (MMMM), which breaks the convention of no more than three consecutive identical symbols. Extended systems exist that use a bar over a letter to multiply by 1,000, but these are not universally standardized and are rarely used in modern contexts.
Why is 4 written as IV instead of IIII?
IV is the subtractive form: placing a smaller value before a larger one means subtract rather than add. This convention was adopted to keep numerals concise and readable. However, IIII does appear on some clock faces — a tradition maintained for visual balance and to match the VIII on the opposite side.
Where are Roman numerals still used today?
Roman numerals appear on clock faces, in book prefaces and chapter numbering, on film and TV copyright dates, in names of monarchs and popes (King Charles III, Pope Francis I), in Super Bowl and Olympic Game numbering, and in formal outlines. They are also commonly used to number the introductory pages of books before the main text begins.
What is the largest number this converter handles?
This converter handles integers from 1 to 3999, which covers the full range of standard Roman numerals. Zero has no Roman numeral representation (the concept of zero didn't exist in Roman mathematics). Negative numbers are also outside the scope of Roman notation.