Roman Numeral Converter

Convert between Roman numerals and decimal numbers with this free online tool.

Decimal Number (1-3999)

Roman Numeral

How to Use the Roman Numeral Converter

Decimal to Roman

Select the "Decimal to Roman" tab
Enter a decimal number between 1 and 3999
Click "Convert" to see the equivalent Roman numeral
Click the copy button to copy the result to your clipboard

Roman to Decimal

Select the "Roman to Decimal" tab
Enter a valid Roman numeral (e.g., MCMXCIV)
Click "Convert" to see the equivalent decimal number
Click the copy button to copy the result to your clipboard

Roman Numeral System

The Roman numeral system is an ancient number system that uses combinations of letters from the Latin alphabet to represent numbers. The basic symbols are:

100

500

1000

Roman numerals are typically written from largest to smallest, from left to right. However, there are subtractive combinations where a smaller numeral before a larger one means subtraction (e.g., IV is 4, not 6).

Common Roman Numeral Examples

100

500

1000

MCMXCIV

1994

MMXXIII

2023

FAQs

Why can't I convert numbers larger than 3999?

Traditional Roman numerals only go up to 3,999 (MMMCMXCIX). For larger numbers, additional notation is needed, which is not standardized.

Are Roman numerals still used today?

Yes, Roman numerals are still used in various contexts such as clock faces, book chapters, movie sequel numbering, and formal documents.

What are the rules for Roman numerals?

The basic rules are: numerals are usually written largest to smallest from left to right; when a smaller numeral appears before a larger one, it's subtracted (e.g., IV = 4); a numeral cannot be repeated more than three times in a row.