Roman Numeral Converter
Convert between decimal numbers and Roman numerals (1–3999).
Your Input
Choose conversion direction, enter a decimal (1–3999) or a Roman numeral, then click Convert to see the result and step-by-step solution.
Complete User Guide
What are Roman Numerals?
Roman numerals are a numeral system that originated in ancient Rome. They use combinations of letters from the Latin alphabet (I, V, X, L, C, D, M) to represent numbers.
How to Use
- Select conversion direction (Decimal to Roman or Roman to Decimal)
- Enter the value to convert
- Click Convert to see the result and step-by-step solution
- Use Reset to clear and hide results
Roman Numeral Symbols
I = 1 V = 5 X = 10 L = 50 C = 100 D = 500 M = 1000
Subtractive Notation
IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900
Rules
- Symbols are written from largest to smallest
- No more than 3 identical symbols in a row
- Only I, X, C can be used for subtraction
- V, L, D cannot be subtracted
Common Examples
1 = I 4 = IV 9 = IX 49 = XLIX 100 = C 500 = D 1000 = M 2024 = MMXXIV
Important Notes
- Decimal numbers must be between 1 and 3999
- Roman numerals are case-insensitive
- Invalid formats will be rejected
- Standard Roman numeral rules apply
Common Applications
- Clock faces and timepieces
- Book chapter numbering
- Movie and TV series titles
- Monument inscriptions
- Educational purposes