Roman Numeral Converter

How to Use This Converter

Type any whole number from 1 to 3,999 into the input box above. The Roman numeral equivalent appears instantly as you type — no button press needed. Hit the Copy button to copy the result to your clipboard.

To go the other direction, click Roman → Number and type a Roman numeral like XIV or MMXXIV. The converter validates your input and shows the decimal value immediately.

Roman Numeral Rules

Roman numerals follow a simple additive-subtractive system:

• Additive: symbols written left-to-right add up. VIII = 5 + 1 + 1 + 1 = 8.
• Subtractive: a smaller symbol before a larger one subtracts. IV = 5 − 1 = 4.
• Valid subtractive pairs: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).
• No more than three of the same symbol in a row — so 4 is IV, not IIII.

Common Conversions