Roman Numerals Converter

Roman numerals to decimal number conversion

Roman Numerals Converter

Enter Roman numeral to Convert

How to Use Roman to Decimal Converter

What are Roman Numerals

Roman numerals are a numeral system that originated in ancient Rome and are still used today in various applications. The basic symbols are: I (1), V (5), X (10), L (50), C (100), D (500), M (1000).

Basic Rules of Roman Numeration

  • Addition: When a smaller symbol follows a larger one, they are added (VI = 6)
  • Subtraction: When a smaller symbol precedes a larger one, it is subtracted (IV = 4)
  • Repetition: Symbols I, X, C, M can be repeated up to three times in a row (exception — the letter M in classic notation)
  • Limited subtraction: Only I, X, C can precede larger symbols

Popular Roman Numerals and Their Values

The most commonly used Roman numerals in everyday life:

  • I = 1
  • II = 2
  • III = 3
  • IV = 4
  • V = 5
  • VI = 6
  • IX = 9
  • X = 10
  • XX = 20
  • L = 50
  • C = 100
  • CD = 400
  • D = 500
  • M = 1000
  • MCMLIV = 1954
  • MMXXVI = 2026

Where Roman Numerals Are Used Today

Roman numerals are still widely used in:

  • Clocks: On traditional clock faces
  • Movies and books: For numbering volumes, chapters, parts
  • Sports: Olympic Games, Super Bowl
  • Architecture: Dates on buildings and monuments
  • Monarchy: Names of rulers (Elizabeth II)
  • Education: Section numbering in documents

How to Convert Complex Roman Numbers

To convert large Roman numbers, follow this algorithm:

  1. Break the number into groups of symbols
  2. Determine the value of each group
  3. Apply addition and subtraction rules
  4. Sum all values

Example: MCMXC = M (1000) + CM (900) + XC (90) = 1990

Common Mistakes with Roman Numerals

  • Using more than three identical symbols in a row
  • Incorrect application of subtraction rules
  • Confusion between similar symbols
  • Ignoring the order of symbols

See Also

Roman Numerals Converter

This calculator will help you to convert roman numerals to decimal numbers. For example, it can help you find out what number is Roman numeral IV? (The answer is: 4). Enter roman numeral (e.g. 'IV') and hit the 'Convert' button.
Roman numerals list: I=1 V=5 X=10 L=50 C=100 D=500 M=1000

FAQ

How do you read a Roman numeral?

Add up the symbol values from left to right — I=1, V=5, X=10, L=50, C=100, D=500, M=1000 — and subtract a smaller symbol that stands in front of a larger one. XLVII = (50 − 10) + 5 + 1 + 1 = 47.

Which subtractive combinations are allowed?

Only six: IV=4, IX=9, XL=40, XC=90, CD=400 and CM=900. Just I, X and C are ever subtracted, and only from the two symbols directly above them, so 49 is written XLIX and never IL.

What is the largest number Roman numerals can express?

3999 = MMMCMXCIX with the classic symbols: M may not be repeated more than three times and there is no symbol for 5000. There is no symbol for zero either — medieval scribes wrote the letter N, short for the Latin nulla.