Roman Numeral Converter

Convert between Arabic numbers and Roman numerals. Supports values 1 through 3999 with step-by-step conversion breakdown. 100% client-side.

Quick Examples

Roman Numeral Values

I1
IV4
V5
IX9
X10
XL40
L50
XC90
C100
CD400
D500
CM900
M1,000

How to Use the Roman Numeral Converter

  1. Select your conversion direction: Number to Roman or Roman to Number.
  2. Enter a number (1-3999) or Roman numeral.
  3. Click Convert to see the result.
  4. Toggle Show Steps to see how the conversion works.

Roman Numeral Rules

  • I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000
  • Subtractive notation: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900
  • A smaller numeral before a larger one means subtraction
  • Maximum standard value is 3999 (MMMCMXCIX)