Roman Numeral Converter
Convert between Roman numerals and Arabic numbers. Supports values from 1 to 3,999 with instant bidirectional conversion.
About the Roman Numeral Converter
Our free online Roman numeral converter instantly converts between Roman numerals and Arabic (decimal) numbers. Type a number like 2024 to get MMXXIV, or paste Roman numerals like MCMXCVIII to get 1998. Supports all standard Roman numeral combinations from 1 to 3,999. Perfect for students learning Roman numerals, historians, clock enthusiasts, and anyone dealing with Roman numeral dates or references.
Features
- Convert Arabic numbers to Roman numerals
- Convert Roman numerals to Arabic numbers
- Supports values from 1 to 3,999
- Auto-detection — type number or Roman numeral
- Real-time conversion as you type
- Copy result to clipboard
- 100% private — browser-only processing
How to use this tool
The Roman Numeral Converter works right in your browser — no signup, no installation. Follow these steps:
- Type a number (like 2024) or Roman numeral (like MMXXIV) into the input area.
- The tool auto-detects which direction to convert.
- The converted result appears instantly below.
- Click Copy to save the result to your clipboard.
Frequently asked questions
What is the largest Roman numeral supported?
The tool supports Roman numerals up to 3,999 (MMMCMXCIX). Larger numbers require special notation (like a vinculum/bar over letters for ×1,000) which is not standard in basic Roman numeral systems.
How do Roman numerals work?
Roman numerals use seven letters: I=1, V=5, X=10, L=50, C=100, D=500, M=1,000. Numbers are formed by combining letters, with smaller values before larger values indicating subtraction (IV=4, IX=9, XL=40, XC=90, CD=400, CM=900).
Why is 4 written as IV instead of IIII?
Roman numerals use subtractive notation: I before V (5) means 5-1=4. This is the standard form used today. However, IIII was commonly used in ancient Rome and still appears on some clock faces.
Using the results
Use the Roman Numeral Converter to transform supported text or data formats in your browser. Review the output before replacing your original, since some conversions change formatting or discard information.