Roman Numeral Converter

Convert between Roman numerals and decimal numbers instantly

Enter a Number or Roman Numeral

Roman Numeral Reference

RomanValueRule
I1Base unit
IV4Subtractive: 5 - 1
V5Base symbol
IX9Subtractive: 10 - 1
X10Base symbol
XL40Subtractive: 50 - 10
L50Base symbol
XC90Subtractive: 100 - 10
C100Base symbol
CD400Subtractive: 500 - 100
D500Base symbol
CM900Subtractive: 1000 - 100
M1000Base symbol

Frequently Asked Questions

What is the range for Roman numerals?
Standard Roman numerals represent numbers from 1 to 3999. The number 4000 and above would require a bar notation (vinculum) which is not part of the standard system.
How does subtractive notation work?
When a smaller numeral appears before a larger one, it is subtracted. For example, IV = 5 - 1 = 4, and XC = 100 - 10 = 90. Only I, X, and C can be used subtractively.
Can Roman numerals represent zero?
No. The Roman numeral system has no symbol for zero. It was developed before the concept of zero was widely adopted in European mathematics.
Where are Roman numerals still used today?
Roman numerals are commonly used in clock faces, book chapters, movie sequels, Super Bowl numbering, copyright dates, outlines, and formal document numbering.
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