Roman Numeral Converter – Free Online Number to Roman Numerals Tool

Convert any number between 1 and 3,999 to its Roman numeral equivalent — or decode Roman numerals back to Arabic numbers — instantly in your browser. Supports all standard subtractive notation pairs (IV, IX, XL, XC, CD, CM). Perfect for students, historians, designers, clock makers, and anyone working with Roman numerals. No login or installation required.

Conversion Direction

Quick Reference

I
1
V
5
X
10
L
50
C
100
D
500
M
1000
IV
4
IX
9
XL
40
XC
90
CD
400

How to Use the Roman Numeral Converter

Operation modes:

  • Number → Roman: Enter any integer from 1 to 3999. The result uses standard subtractive notation (e.g. 4 → IV, 2024 → MMXXIV).
  • Roman → Number: Enter a valid Roman numeral string (e.g. XLII → 42). Letters are case-insensitive.

How to use:

  1. Select the conversion direction with the radio buttons.
  2. Type or paste your value in the Input area.
  3. The result appears instantly. Use Copy to copy it.

Rules & limits:

  • Only integers between 1 and 3,999 are supported (standard Roman numeral range).
  • Valid characters: I V X L C D M (uppercase or lowercase).
  • Subtractive pairs like IV, IX, XL, XC, CD, CM are fully supported.