Roman Numeral Converter
Convert numbers to Roman numerals and back.
Convert numbers to Roman numerals and Roman numerals back to numbers, anywhere from 1 to 3999. It auto-detects which way you're converting and validates the numeral.
Type a number (1–3999) to get the Roman numeral, or a Roman numeral to get the number — it auto-detects.
Runs entirely in your browser — nothing is uploaded.
How to use the roman numeral converter
- 1Type a number (1–3999) or a Roman numeral.
- 2The conversion appears instantly.
- 3Copy the result.
Frequently asked questions
What's the largest number supported?
Standard Roman numerals go up to 3999 (MMMCMXCIX); larger values need overlines, which aren't part of the basic system.
Does it validate Roman numerals?
Yes — malformed numerals like 'IIII' or 'VX' are rejected, so only correctly formed numerals convert.