Online Roman Numerals Converter

What is the Roman Numerals Converter?

The Roman Numerals Converter is a tool that allows you to convert between the ancient Roman numeral system and our modern decimal (base-10) number system. This converter works in both directions, enabling you to translate Roman numerals like MCMXCIV to decimal numbers like 1994, or convert decimal numbers back to their Roman numeral representation.

Understanding Roman Numerals

Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Unlike our modern decimal system, which uses place value and a zero digit, Roman numerals are based on certain letters which represent fixed values.

Basic Roman Numeral Symbols

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

Roman Numeral Rules

Roman numerals follow specific rules for combining symbols:

1. Additive Principle: When a symbol appears after a symbol of greater or equal value, it is added to the total.
   Example: VI = 5 + 1 = 6
2. Subtractive Principle: When a symbol appears before a symbol of greater value, it is subtracted from the total.
   Example: IV = 5 - 1 = 4
3. Repetition Rule: Symbols I, X, C, and M can be repeated up to three times in succession.
   Example: III = 1 + 1 + 1 = 3
4. Non-Repetition Rule: Symbols V, L, and D cannot be repeated.
   Example: VV is invalid; instead, use X for 10
5. Subtraction Rule: Only certain combinations use the subtractive principle:
   • IV = 4 (not IIII)
   • IX = 9 (not VIIII)
   • XL = 40 (not XXXX)
   • XC = 90 (not LXXXX)
   • CD = 400 (not CCCC)
   • CM = 900 (not DCCCC)