Roman Numerals Converter
Convert Arabic numbers to Roman numerals instantly with our free online converter. Perfect for students, teachers, and history enthusiasts. Fast, accurate, and easy to use.
Roman Numerals Converter
Convert between Roman numerals and decimal numbers instantly. Select the conversion type, enter a value, and get the result.
Select the number system to convert from
Select the number system to convert to
Enter the value to convert (1-3999 for decimal, valid Roman numerals only)
How to Convert Roman Numerals?
Roman numerals are a numeral system that originated in ancient Rome. To convert between Roman numerals and decimal numbers:
1. Decimal to Roman: Break down the number into thousands, hundreds, tens, and ones. Convert each part using the Roman numeral symbols (I, V, X, L, C, D, M).
2. Roman to Decimal: Read the Roman numeral from left to right. Add the values of symbols, but if a smaller symbol appears before a larger one, subtract the smaller value instead.
Roman Numeral System Principles
1. Basic Symbols
Roman numerals use seven basic symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). These symbols are combined to represent any number.
2. Additive Notation
When symbols are arranged from largest to smallest (left to right), their values are added. For example: VI = 5 + 1 = 6, and LX = 50 + 10 = 60.
3. Subtractive Notation
When a smaller symbol appears before a larger one, subtract the smaller value. Only I, X, and C can be subtracted. Examples: IV = 5 - 1 = 4, IX = 10 - 1 = 9, XL = 50 - 10 = 40, XC = 100 - 10 = 90, CD = 500 - 100 = 400, CM = 1000 - 100 = 900.
4. Repetition Rules
- I, X, C, and M can be repeated up to three times consecutively
- V, L, and D cannot be repeated
- Repetition means addition: III = 3, XXX = 30, CCC = 300
5. Subtraction Rules
- Only I, X, and C can be used as subtractive numerals
- I can be subtracted from V and X only
- X can be subtracted from L and C only
- C can be subtracted from D and M only
- Only one smaller symbol can appear before a larger symbol
6. Limitations
Traditional Roman numerals can represent numbers from 1 to 3999. There is no symbol for zero. Numbers beyond 3999 require special notations (like a bar over numerals for multiplication by 1000).
Roman Numeral Symbols
I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1000
Conversion Examples
1 = I
4 = IV
9 = IX
27 = XXVII
49 = XLIX
99 = XCIX
400 = CD
500 = D
900 = CM
1984 = MCMLXXXIV
2024 = MMXXIV
3999 = MMMCMXCIX
