Roman Numeral Converter

Online two-way converter between Arabic and Roman numerals, supporting values from 1 to 3999.

Conversion

Enter an integer between 1 and 3999
Enter Roman numeral characters (I, V, X, L, C, D, M)

Roman Numeral Reference Table

M1000
CM900
D500
CD400
C100
XC90
L50
XL40
X10
IX9
V5
IV4
I1

Features

The Roman numeral converter supports two-way real-time conversion between Arabic numerals (1-3999) and Roman numerals. Roman numerals originated in ancient Rome and use seven basic symbols (I, V, X, L, C, D, M) combined by specific rules to represent values.

How to Use

  • Enter an Arabic numeral on the left; the corresponding Roman numeral appears on the right automatically.
  • Enter a Roman numeral on the right (case insensitive); the corresponding Arabic numeral appears on the left automatically.
  • Input range is limited to 1 through 3999.
  • An error message is displayed for invalid Roman numeral formats.

Usage Instructions

Features

The Roman numeral converter supports two-way real-time conversion between Arabic numerals (1-3999) and Roman numerals, and provides a reference table of the seven basic symbols (I, V, X, L, C, D, M).

Steps

Enter an Arabic numeral on the left to get the Roman numeral, or enter a Roman numeral on the right (case insensitive) to get the Arabic numeral; the table at the bottom shows the value of each symbol.

Notes

All conversions run locally in the browser; the input range is limited to 1-3999, and invalid Roman numeral formats display an error message.