Roman Numeral Converter
Convert between decimal numbers (1-3999) and Roman numerals instantly. Free online converter with detailed explanations and validation.
Roman Numeral Reference Chart
| Symbol | Value | Notes |
|---|---|---|
| I | 1 | Can be repeated up to 3 times |
| V | 5 | Cannot be repeated |
| X | 10 | Can be repeated up to 3 times |
| L | 50 | Cannot be repeated |
| C | 100 | Can be repeated up to 3 times |
| D | 500 | Cannot be repeated |
| M | 1000 | Can be repeated up to 3 times |
Subtraction Rules
IV = 4 (5 - 1)
IX = 9 (10 - 1)
XL = 40 (50 - 10)
XC = 90 (100 - 10)
CD = 400 (500 - 100)
CM = 900 (1000 - 100)
Common Examples
Bidirectional Conversion
Convert numbers to Roman numerals and back again with full validation and accuracy.
Detailed Explanations
See step-by-step breakdowns of how each conversion is calculated.
Validation
Automatic validation ensures only valid Roman numerals and numbers (1-3999) are accepted.
Frequently Asked Questions
How do I convert a number to Roman numerals?
Select “Number → Roman” mode, enter any number between 1 and 3999, and the Roman numeral equivalent will appear instantly with a step-by-step explanation of the conversion.
Can I convert Roman numerals back to numbers?
Yes! Select “Roman → Number” mode, enter a valid Roman numeral (e.g., MCMXC), and it will be converted to its decimal equivalent with a breakdown of the calculation.
What is the valid range for Roman numeral conversion?
This tool supports conversion for numbers between 1 and 3999. Roman numerals traditionally do not have a standard representation for zero or numbers above 3999.
What are the Roman numeral rules?
Roman numerals use seven basic symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtraction notation is used for 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD), and 900 (CM). Symbols I, X, C can be repeated up to 3 times, while V, L, D cannot be repeated.
Is my data private?
Absolutely! All conversions happen entirely in your browser. Your data never gets sent to any server, ensuring complete privacy and security.