About this tool
Convert numbers to and from Roman numerals.
The Roman Numeral Converter works in both directions. Type a decimal number (1–3999) to see its Roman numeral equivalent, or type a Roman numeral to get the decimal value. Uses standard subtractive notation (IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900) as used on clocks, book chapters, film titles and formal documents.
Example
2024 → MMXXIV · MMXXIV → 2024
How to use
- Type a number (1–3999) or a Roman numeral in the input.
- Conversion appears instantly.
- Switch direction with the toggle.
- Copy the result.
Features
- Number → Roman numeral
- Roman numeral → number
- Supports 1–3999
- Standard subtractive notation
- Validates invalid input
Frequently Asked Questions
Why is there a limit of 3999?+
Standard Roman numerals cannot exceed 3999 without non-standard extensions. The vast majority of Roman numeral usage is within this range.
What does IV mean?+
IV = 4. The subtractive principle means I placed before V reduces the value by 1: 5 − 1 = 4.
Is IIII valid for 4?+
Historically yes (used on some clock faces) but the standard modern form is IV. This converter uses IV.
What year is MCMXCIX?+
MCMXCIX = 1999. M=1000, CM=900, XC=90, IX=9.
Why do some numerals use subtraction (like IV for 4)?+
Subtractive notation shortens numerals and avoids repeating a symbol 4 times. IV (5−1=4) is shorter than IIII. A smaller value before a larger one is subtracted.
What is the largest number supported?+
3,999 (MMMCMXCIX). Numbers above 3,999 require an overline notation not used in standard Roman numerals.