Roman Numeral Converter
Convert between numbers (1–3999) and Roman numerals with a full step-by-step breakdown. Supports both directions: number to Roman and Roman to number.
How to Use This Calculator
- Select conversion direction: Number to Roman or Roman to Number.
- Enter the value in the appropriate field.
- Click "Convert" to see the result and step-by-step breakdown.
- Review the conversion steps to understand how each part was calculated.
Formula
Rules:
- Symbols are placed from largest to smallest (left to right).
- When a smaller symbol precedes a larger one, it is subtracted (e.g., IV = 4, XC = 90).
- Only I, X, C, and M can be repeated (max 3 times).
- Only I, X, and C can be used for subtraction.
Examples
MMXXIV = 1000 + 1000 + 10 + 10 + (5−1) = 2024
MCMXCIX = 1000 + (1000−100) + (100−10) + (10−1) = 1999
XLIX = (50−10) + (10−1) = 49 — Uses subtractive notation to avoid IIII or XXXX.
Frequently Asked Questions
Why is 4 written as IV instead of IIII?
Roman numerals use subtractive notation to avoid repeating a symbol more than three times. IV is more compact and easier to read than IIII.
What is the largest number that can be converted?
This converter handles 1–3999. For larger numbers, Romans used a vinculum (bar) over symbols to multiply by 1000, but this extended notation is not widely standardized.
Is there a Roman numeral for zero?
No. The Roman numeral system has no representation for zero. The concept of zero came later from Indian/Arabic mathematics.
Are Roman numerals still used today?
Yes. They are used for clock faces, movie release years, monarch names (Elizabeth II), book chapters, and sporting events (Super Bowl, Olympics).