Roman Numeral Converter
Convert numbers to Roman numerals and back, with the rules explained.
Formula
I=1, V=5, X=10, L=50, C=100, D=500, M=1000
Tips
- Subtractive pairs are limited to IV, IX, XL, XC, CD and CM. IC for 99 is not valid — it is XCIX.
- A symbol repeats at most three times: 4 is IV, not IIII. Clock faces using IIII are a decorative exception.
- There is no zero and no way to write a fraction, which is a large part of why the system was displaced.
Frequently asked questions
Why stop at 3999?
Beyond that you need a vinculum — an overbar meaning "multiply by a thousand" — which has no single agreed digital representation. Most converters stop where the unambiguous notation does.