Roman Numeral Converter
Convert Arabic numbers to Roman numerals and back. Supports numbers 1–3999 using the standard Roman numeral system.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
Roman numeral
XLII
Reference symbols
| Roman | Value |
|---|---|
| M | 1000 |
| CM | 900 |
| D | 500 |
| CD | 400 |
| C | 100 |
| XC | 90 |
| L | 50 |
| XL | 40 |
| X | 10 |
| IX | 9 |
| V | 5 |
| IV | 4 |
| I | 1 |
This tool provides general unit conversions for everyday and educational use. For regulated, legal, or scientific applications, verify conversion factors against the applicable official standard.
About the Roman Numeral Converter
The Roman numeral converter changes whole numbers from 1 to 3,999 into Roman numerals and back. It applies the subtractive rules — IV = 4, IX = 9, XL = 40, XC = 90, CD = 400 and CM = 900 — and rejects invalid forms. Roman numerals appear in clock faces, book chapters, film copyright dates and events such as the Super Bowl.
How to use it
- 1Choose Arabic → Roman or Roman → Arabic.
- 2Enter the number or numeral.
- 3Read the converted value.
- 4Copy, share or print the result with the buttons below it.
Worked example
2026 = MMXXVI and 1999 = MCMXCIX.
How it works
Roman numeral rules
Symbols: 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.
Common use cases
- Reading dates in film credits and buildings
- Numbering chapters and outlines
- Homework and puzzles
Frequently asked questions
A:2024 = MMXXIV.
A:The standard Roman system has no symbol for 5000+. Numbers above 3999 require special notation not supported in classical usage.
Reviewed for accuracy · Last updated October 7, 2026
Conversion factors are based on internationally defined SI units and standard metric/imperial equivalence tables.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
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