🏛️ Roman Numeral Converter

About Roman Numerals

Roman numerals originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are represented by combinations of letters from the Latin alphabet.

Basic Symbols

Rules for Combining Symbols

• Symbols are placed from left to right in order of value, starting with the largest. In general, the values are added together (e.g., VI = 5 + 1 = 6, LXX = 50 + 10 + 10 = 70).
• Subtractive Notation: To avoid repeating a symbol four times (like IIII), a smaller value symbol can be placed before a larger value symbol. This indicates subtraction.
  • I can be placed before V (4) and X (9).
  • X can be placed before L (40) and C (90).
  • C can be placed before D (400) and M (900).
  Example: MCMXCIV = 1000 (M) + 900 (CM) + 90 (XC) + 4 (IV) = 1994.
• A symbol representing 10^x (I, X, C) cannot be placed before a symbol more than 10 times greater (e.g., IM for 999 is invalid).
• Only one smaller value symbol can be placed before a larger value symbol (e.g., IIX for 8 is invalid).
• The symbols V, L, and D are never used in subtractive notation.

Limitations

This converter handles standard Roman numerals for numbers between 1 and 3999. Larger numbers or variations using bars (vinculum) for multiplication are not supported.

How to Use

1. To convert a number to Roman: Enter a number between 1 and 3999 in the "Number" field and click "Convert to Roman".
2. To convert a Roman numeral to a number: Enter a valid Roman numeral (using I, V, X, L, C, D, M) in the "Roman Numeral" field and click "Convert to Number".
3. The result will appear in the blue box below the input sections.
4. Error messages will appear if the input is invalid or outside the supported range.