How does Roman numeral conversion work?

It maps numeric values to symbols (I, V, X, L, C, D, M) using additive and subtractive combinations.

What is the subtractive rule?

A smaller value before a larger one is subtracted — IV means 4, not 6.

What's the largest number in standard Roman numerals?

Typically 3,999 (MMMCMXCIX); larger numbers need special notation.

Roman Numeral Converter | CalculatorLabs.net

Roman Numeral Converter

Convert whole numbers to Roman numerals, or Roman numerals back to numbers.

What Is the Roman Numeral Converter?

This tool converts whole numbers into Roman numerals, or Roman numerals back into standard numbers, following the classical subtractive notation used since ancient Rome (e.g., IV for 4, IX for 9).

Formula

Roman numerals are built from symbol values (I=1, V=5, X=10, L=50, C=100, D=500, M=1000), with a smaller symbol before a larger one subtracted rather than added — for example, IV = 5 − 1 = 4.

How to Use This Calculator

Choose a direction: Number → Roman, or Roman → Number.
Enter your value (a whole number from 1–3,999, or a Roman numeral).
Click Calculate to see the conversion.

Worked Example

The number 1994 converts to MCMXCIV: M (1000) + CM (900) + XC (90) + IV (4).

Tips

Standard Roman numerals only represent whole numbers from 1 to 3,999 — there's no traditional symbol for zero or negative numbers.