Roman Numeral Converter
The Roman Numeral Converter converts between Roman numeral notation and ordinary decimal numbers where supported. Roman numerals use combinations of letters such as I, V, X, L, C, D, and M to represent values.
How to use this calculator
- Choose the conversion direction provided by the calculator.
- Enter a valid Roman numeral or decimal number.
- Review the converted representation.
- Check the notation when working with unusually large values or non-standard Roman numeral conventions.
Roman numeral notation
Common values include I=1, V=5, X=10, L=50, C=100, D=500, and M=1000.
- Roman numerals are generally formed by combining symbols from larger values to smaller values.
- Certain smaller symbols placed before larger symbols represent subtraction, such as IV for 4 and IX for 9.
- Modern Roman numeral notation follows conventional forms, although historical Roman inscriptions used additional variations.
Worked examples
Example: 14
The decimal number 14 can be represented using X for 10 and IV for 4.
10 + 4 = XIV
14 is XIV in Roman numerals.
Example: 49
The standard modern representation uses XL for 40 and IX for 9.
40 + 9 = XLIX
49 is XLIX in Roman numerals.
Understanding the result
Roman numerals are not a positional number system like decimal or binary notation.
Symbol order matters. A smaller value before a larger value can indicate subtraction under standard notation.
There are historical and stylistic variations, so modern converters generally follow commonly accepted conventional forms.
Important notes
The calculator uses conventional Roman numeral notation rather than attempting to reproduce every historical variation.
Very large values can involve conventions that differ from the standard forms commonly taught today.
When Roman numerals are being used in a historical or academic context, check the convention appropriate to that source.
Frequently asked questions
What does X mean in Roman numerals?
X represents 10.
Why is 4 written as IV?
Under standard subtractive notation, I before V means 5 minus 1, giving 4.
What is 100 in Roman numerals?
100 is represented by C.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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Roman numeral converter use cases
Use a Roman numeral converter when you need to write a number in a traditional numeral form for lists, chapters, dates, puzzles, games, or historical references. The converter follows standard Roman numeral notation and makes the result easy to copy.
Related number tools can help when you need to move between representations. Try the number base calculator for binary, decimal, hexadecimal, and other base conversions, or the fraction calculator for rational-number work.
This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.