How it works
Seamlessly convert between standard Arabic numerals and classical Roman numeral notations.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
3-
?number=Decimal Number (1-3999)Number · Optional · Default: 2,024
-
?roman=Roman SymbolsText · Optional · Default:
-
?mode=ModeChoice · Optional · Default: toRoman
Outputs
1-
resultResultText · Primary output
result contains the calculator’s complete rendered result area, including its visible result cards, tables, charts, and messages.
Convert between Arabic numbers and ancient Roman numerals
Description
The Roman Numeral Converter is a dual-purpose tool for translation between modern (Arabic) numbers and the numeral system of Ancient Rome. Roman numerals are still used today in names (like monarchs or sports events), architectural dates on buildings, and clock faces. This tool supports bidirectional conversion for integers ranging from 1 to 3,999, following the standard “subtractive” logic used in modern notation.
Inputs
- Mode: Choose “Number to Roman” or “Roman to Number.”
- Value: Enter the number (e.g.,
2024) or the numeral string (e.g.,MMXXIV).
Outputs
- Result: The converted value.
Chart
- N/A: This tool provides a direct string-to-number translation.
“Good to Know”
- The Symbols:
- I: 1
- V: 5
- X: 10
- L: 50
- C: 100
- D: 500
- M: 1000
- The Subtractive Rule: If a smaller value appears before a larger one, it is subtracted (e.g.,
IVis 4,XCis 90). If it appears after, it is added (e.g.,VIis 6). - Upper Limit: Standard Roman notation without special horizontal bars over the letters (vinculum) is limited to 3,999.
Examples
Example 1: Modern Year
- Input: 2024
- Output: MMXXIV
Example 2: Classics
- Input: IX
- Output: 9
Example 3: Complex String
- Input: MCMLXXXV
- Output: 1985