What is the range of supported values?

Standard Roman numeral notation covers 1 to 3999. Zero and negative numbers have no Roman numeral representation. The largest value, 3999, is written as MMMCMXCIX.

How does the auto-detect work?

If the input consists only of digits, it is treated as a decimal number to be converted to Roman numerals. If the input contains only valid Roman numeral characters (I, V, X, L, C, D, M), it is converted to decimal.

What are the subtractive notation rules?

Roman numerals use subtractive notation for certain pairs: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. A smaller value preceding a larger one indicates subtraction rather than addition.

Roman Numeral Converter

Convert between Roman numerals and decimal numbers in both directions.

Input (decimal number or Roman numeral)

Enter a number (1-3999) to get Roman numerals, or Roman numerals to get the decimal value.

Decimal

Roman Numeral

XIV

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FAQ

What is the range of supported values?: Standard Roman numeral notation covers 1 to 3999. Zero and negative numbers have no Roman numeral representation. The largest value, 3999, is written as MMMCMXCIX.
How does the auto-detect work?: If the input consists only of digits, it is treated as a decimal number to be converted to Roman numerals. If the input contains only valid Roman numeral characters (I, V, X, L, C, D, M), it is converted to decimal.
What are the subtractive notation rules?: Roman numerals use subtractive notation for certain pairs: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. A smaller value preceding a larger one indicates subtraction rather than addition.

The Roman Numeral Converter automatically detects input type: numeric input is converted to Roman numerals, while Roman numeral input is converted to decimal. Supports values from 1 to 3999 — the full standard range of Roman numeral notation. Results include a one-click copy button.