Roman Numeral Calculator
Convert between standard integers and Roman Numerals. Supports addition, subtraction, and historical notation rules for values up to 3,999.
Swap between modern numbers and ancient Roman symbols with ease: Step 1: Enter a number (e.g., 2024) or a Roman string (e.g., MMXXIV). Step 2: Choose the conversion direction or an arithmetic operation (+, -, etc.). Step 3: Click "Convert" or "Calculate." Step 4: Review the results. The tool will provide the breakdown of each symbol's value and the final output in both formats.
The 7 Base Symbols
| Symbol | Value | Meaning |
|---|---|---|
| I | 1 | Unit |
| V | 5 | Unit |
| X | 10 | Ten |
| L | 50 | Fifty |
| C | 100 | Hundred |
| D | 500 | Five hundred |
| M | 1,000 | Thousand |
Subtractive Notation
| Symbol | Value | Rule |
|---|---|---|
| IV | 4 | I before V |
| IX | 9 | I before X |
| XL | 40 | X before L |
| XC | 90 | X before C |
| CD | 400 | C before D |
| CM | 900 | C before M |
A smaller symbol placed before a larger one is subtracted, not added.
Notable Examples
| Arabic | Roman |
|---|---|
| 2,024 | MMXXIV |
| 1,999 | MCMXCIX |
| 1,776 | MDCCLXXVI |
| 3,999 | MMMCMXCIX |
Quick Rules
Symbols repeat up to 3 times in a row (III = 3, not IIII).
V, L, D are never repeated or subtracted from.
Only I, X, C, M may be repeated.
Valid range is 1 – 3999 (I to MMMCMXCIX).
Roman numerals use seven symbols: I(1), V(5), X(10), L(50), C(100), D(500), M(1000). Rules: 1. Addition: If a smaller symbol follows a larger one, add them (VI = 5+1=6). 2. Subtraction: If a smaller symbol precedes a larger one, subtract it (IV = 5-1=4). 3. Repetition: Symbols like I, X, C, and M can be repeated up to three times. 4. Scale: A bar over a symbol (vinculum) multiplies its value by 1,000 (though usually not used for numbers under 4,000).
The Roman Numeral Calculator is a handy tool for history students, clock designers, and movie fans (tracking copyright years). While the Roman system is no longer used for complex math due to its lack of a zero and positional value, it remains a symbol of prestige and tradition. Our tool ensures you follow the strict 'subtractive notation' rules that define the standard modern interpretation of the system.
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