Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers. Supports standard values from 1 to 3999 with validation and symbol breakdown.
Convert Roman numerals both ways
English search intent expects a two-way converter: enter a number and get a Roman numeral, or paste a Roman numeral and get the Arabic number with validation.
- Convert numbers from 1 to 3999 into standard Roman numerals.
- Convert valid Roman numerals using I, V, X, L, C, D, and M back into numbers.
- Check the symbol breakdown and round-trip result to catch invalid notation.
M contributes 1000, X contributes 10, and IV is the subtractive form for 4.
Standard Roman numeral rules
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
- I, X, C, and M can repeat up to three times in a row.
- V, L, and D do not repeat.
- Allowed subtractive pairs are IV, IX, XL, XC, CD, and CM.
- Zero, negative numbers, fractions, and overline notation are outside this converter's scope.
Frequently Asked Questions
Sources and References
Calculations are based on the listed reference sources. Links open in a new tab.
Related Tools
Calculate with very large integers using arbitrary precision. Add, subtract, multiply, divide, find remainders, powers, GCD, LCM, and factorials.
Round numbers to decimal places, whole numbers, or a nearest multiple. Compare half-away, half-even, ceiling, floor, and truncation results.
Raise a base to a power, including negative exponents and exact fractional exponents such as 1/2 and 1/3. Includes scientific notation and reciprocal output.
Use a free basic calculator for everyday arithmetic: add, subtract, multiply, divide, percentages, sign changes, copyable results, keyboard input, and local history.