Roman Numeral Converter
Convert between Roman numerals and Arabic numbers. Supports values from 1 to 3999.
Number to Roman
Roman to Number
Roman Numeral Reference Chart
| Roman | Value | Rule |
|---|---|---|
| I | 1 | Base symbol |
| IV | 4 | Subtractive: I before V |
| V | 5 | Base symbol |
| IX | 9 | Subtractive: I before X |
| X | 10 | Base symbol |
| XL | 40 | Subtractive: X before L |
| L | 50 | Base symbol |
| XC | 90 | Subtractive: X before C |
| C | 100 | Base symbol |
| CD | 400 | Subtractive: C before D |
| D | 500 | Base symbol |
| CM | 900 | Subtractive: C before M |
| M | 1,000 | Base symbol |
How to Use the Roman Numeral Converter
1. Number to Roman: Enter any number between 1 and 3999 in the left panel and click "Convert to Roman" to get the Roman numeral equivalent.
2. Roman to Number: Enter a Roman numeral (using I, V, X, L, C, D, M) in the right panel and click "Convert to Number" to get the Arabic number.
3. Reference the chart below the converter to understand the basic symbols and subtractive notation rules.
Frequently Asked Questions
Why is the limit 3999?
Standard Roman numerals only go up to 3999 (MMMCMXCIX). Numbers 4000 and above historically required special notation such as a bar over the numeral (vinculum) to indicate multiplication by 1000.
What is subtractive notation?
Subtractive notation places a smaller numeral before a larger one to indicate subtraction. For example, IV = 4 (5 - 1), IX = 9 (10 - 1), XL = 40 (50 - 10), XC = 90 (100 - 10), CD = 400 (500 - 100), and CM = 900 (1000 - 100).
Is there a Roman numeral for zero?
No. The Roman numeral system does not have a symbol for zero. The concept of zero was introduced much later by Indian and Arabic mathematicians.