Roman Numeral Converter

Decode the Past, Convert for the Future

Arabic to Roman

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Roman to Arabic

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About 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. Numbers in this system are represented by combinations of letters from the Latin alphabet.

How Roman Numerals Work

The Roman numeral system uses seven letters to represent numbers:

Roman Numeral	Arabic Number
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

Basic Rules of Roman Numerals

When a smaller numeral appears before a larger one, it is subtracted (e.g., IV = 4, IX = 9).
When a smaller numeral appears after a larger one, it is added (e.g., VI = 6, XI = 11).
The same symbol cannot be used more than three times in a row (e.g., III = 3 is valid, but IIII = 4 is not).
Only I, X, and C can be used for subtraction (e.g., V cannot be written as VX).
Subtraction can only be done with numerals that are powers of 10 (I, X, C).

Examples

III = 1 + 1 + 1 = 3
IV = 5 - 1 = 4
IX = 10 - 1 = 9
XL = 50 - 10 = 40
XC = 100 - 10 = 90
CD = 500 - 100 = 400
CM = 1000 - 100 = 900
MMXXIII = 1000 + 1000 + 10 + 10 + 1 + 1 + 1 = 2023

Modern Uses of Roman Numerals

While Roman numerals are not commonly used for calculations today, they still appear in several contexts:

Clock faces (e.g., IIII or IV for 4 o'clock)
Book chapters and volume numbers
Movie sequels and video game titles (e.g., Final Fantasy XV)
Building construction years and cornerstones
Numbering of sporting events (e.g., Super Bowl LVII)

Limitations of Roman Numerals

The Roman numeral system has several limitations that led to its replacement by the Arabic numeral system:

No concept of zero (0 wasn't introduced to Europe until the Middle Ages)
Difficult to perform arithmetic operations
Limited range (though extensions exist for larger numbers)
No place value system makes large numbers cumbersome