Roman Numeral Converter
Convert between Arabic numbers (1-3999) and Roman numerals (I-MMMCMXCIX).
Arabic to Roman
Convert Arabic numbers (1-3999) to Roman numerals
Roman to Arabic
Convert Roman numerals to Arabic numbers
Roman Numeral Reference
Basic symbols and their values
I
1
V
5
X
10
L
50
C
100
D
500
M
1000
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Quick Examples
Rules
📝 Additive Principle
When a smaller value follows a larger, add them: VI = 6
➖ Subtractive Principle
When a smaller value precedes a larger, subtract: IV = 4
🔢 Repetition
I, X, C, M can repeat up to 3 times: III = 3
🚫 No Repetition
V, L, D never repeat
Common Patterns
4 = IV, 9 = IX
Subtractive notation
40 = XL, 90 = XC
Tens subtractive
400 = CD, 900 = CM
Hundreds subtractive
Historical Facts
🏛️ Used in Ancient Rome from 8th century BC
📅 Still used today for dates, clocks, and numbering
👑 Common in royal names (Elizabeth II)