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Roman Numeral Converter

Roman Numeral Converter

Easily convert between Roman numerals and decimal numbers. Perfect for historical research, educational purposes, or understanding ancient numeric systems.

Enter a number between 1 and 3999
Roman Numeral:
-
Use symbols I, V, X, L, C, D, M (case insensitive)
Decimal Number:
-

Roman Numeral Reference

I
1
V
5
X
10
L
50
C
100
D
500
M
1000

How to Use

1

Choose conversion direction

Select whether you want to convert from decimal to Roman numerals or from Roman numerals to decimal.

2

Enter your number

Type a decimal number (1-3999) or a valid Roman numeral into the input field.

3

Convert and view results

Click the convert button to see the result, which you can then copy to clipboard if needed.

Understanding Roman Numerals

Roman numerals are a numeral system that originated in ancient Rome. Unlike our current decimal system which uses position and zero, Roman numerals use combinations of letters from the Latin alphabet to signify values.

Rules for Roman Numerals
  1. Basic Symbols: The seven basic symbols are I (1), V (5), X (10), L (50), C (100), D (500), and M (1000).
  2. Additive Principle: When symbols are placed in order of decreasing value, they are added together. For example, XVI = 10 + 5 + 1 = 16.
  3. Subtractive Principle: When a symbol of lower value precedes one of higher value, the lower value is subtracted from the higher. For example, IV = 5 - 1 = 4.
  4. Common Subtractions: Only certain combinations use the subtractive principle: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).
  5. Repetition Rule: Symbols I, X, C, and M can be repeated up to three times in succession. Symbols V, L, and D cannot be repeated.
Examples:
  • 39 = XXX + IX = XXXIX
  • 246 = CC + XL + VI = CCXLVI
  • 1999 = M + CM + XC + IX = MCMXCIX

Roman numerals are still used today in various contexts, including book chapters, clock faces, movie sequel numbering, sporting events like the Olympics and Super Bowl, and in the names of monarchs and popes.

Frequently Asked Questions

What is the largest number that can be represented in Roman numerals?

Traditional Roman numerals can represent numbers from 1 to 3,999. To represent larger numbers, a bar was sometimes placed over a numeral to indicate multiplication by 1,000. However, our converter supports numbers from 1 to 3,999 following standard Roman numeral rules.

Can zero be represented in Roman numerals?

The Roman numeral system does not have a symbol for zero. The concept of zero as a number came to Europe much later, introduced through the Arabic numeral system. Romans didn't need a zero for their counting and commercial purposes.

Are there multiple ways to write the same number in Roman numerals?

In classical Roman numerals, there is only one correct way to write each number. However, historically there have been variations. This converter uses the standard form with subtractive combinations (like IV for 4 rather than IIII) which became standardized in recent centuries.

Why does the converter have a limit of 3,999?

Roman numerals become unwieldy for very large numbers. The limit of 3,999 (MMMCMXCIX) is the largest number that can be represented using the standard Roman numeral symbols without requiring additional notations like bars over letters, which aren't widely supported in digital displays.