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Roman Numeral Converter

Enter a number to see it as a Roman numeral, or enter a Roman numeral to see it as a number.

MMXXVI
2026

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How to use

  1. Enter a whole number from 1 to 3999 to see its Roman numeral.
  2. Or enter a Roman numeral to see its numeric value.
  3. Both fields update live and independently.

What is this tool?

Roman Numeral Converter translates between standard Arabic numbers and Roman numerals using the classic subtractive notation (like IV for 4 and IX for 9). It works in both directions at once, live as you type, and validates that a Roman numeral entry is correctly formed.

Common uses

  • Looking up the Roman numeral for a year, chapter or edition number
  • Decoding a Roman numeral seen on a clock, monument or book
  • Checking a Roman numeral is correctly formatted
  • Formatting a movie sequel, book volume or event number the classic way

FAQ

What's the valid range for numbers?

Standard Roman numerals support whole numbers from 1 to 3999.

Why does my Roman numeral show as invalid?

Roman numerals must follow strict formation rules — the tool checks that your input, when converted, produces exactly that numeral back.

Are lowercase Roman numerals accepted?

Yes, lowercase input is automatically converted to uppercase before validation.