Roman Numeral Converter

Instantly convert between Arabic numbers and Roman numerals

Number to Roman

Convert standard numbers to ancient Roman numerals

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Roman to Number

Convert Roman numerals to standard Arabic numbers

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How to Use This Roman Numeral Converter

Our free online tool makes converting between Roman numerals and Arabic numbers simple:

Number to Roman

Enter any number between 1 and 3999 in the first box and click "Convert to Roman" to see the Roman numeral equivalent.

Roman to Number

Enter valid Roman numerals (I, V, X, L, C, D, M) in the second box and click "Convert to Number" to see the Arabic number.

Roman Numerals Chart

Roman numerals use combinations of letters from the Latin alphabet to represent numbers:

Roman Numeral Number Value Roman Numeral Number Value
I 1 L 50
V 5 C 100
X 10 D 500
XL 40 M 1000

About Roman Numerals

Roman numerals originated in ancient Rome and remained the standard way of writing numbers throughout Europe well into the Late Middle Ages. The system uses combinations of letters from the Latin alphabet to signify values.

Roman numerals are still used today in various contexts including:

  • Clock faces
  • Book chapter numbering
  • Movie production years
  • Monument inscriptions
  • Numbering of sporting events (like the Super Bowl)

Our converter follows the standard rules of Roman numerals:

  • When a smaller numeral appears before a larger one, it's subtracted (IV = 4, IX = 9)
  • When a smaller numeral appears after a larger one, it's added (VI = 6, XI = 11)
  • The same symbol can't be used more than three times in a row (III = 3 is valid, IIII = 4 is not)

Frequently Asked Questions

Classical Roman numerals didn't have a standard way to represent numbers above 3999. While extensions exist (like using a vinculum for larger numbers), our converter focuses on the most commonly used classical form.

Yes, our converter recognizes both uppercase (VII) and lowercase (vii) Roman numerals. The case doesn't affect the value.

This error appears when the input doesn't follow Roman numeral rules. Common issues include: invalid characters, incorrect subtraction (like VX for 5), or too many repeated symbols (like IIII for 4, which should be IV).