Education & Math
Roman Numeral Converter
A Roman numeral converter changes standard numbers into Roman numerals and converts Roman numerals back into numbers. It is useful for schoolwork, outlines, clocks, chapter labels, and quick checks.
Quick answer
The result shows the converted value either as a Roman numeral or a standard number.
What this tells you
- •The result shows the converted value either as a Roman numeral or a standard number.
- •Standard Roman numerals cover the range 1 to 3999.
- •Subtraction rules apply for values like 4 (IV), 9 (IX), 40 (XL), and 90 (XC).
- •This converter assumes modern standard Roman numeral conventions.
How to Use
- 1Enter a whole number to convert it to a Roman numeral.
- 2Enter a Roman numeral to convert it to a standard number.
- 3Review the output and compare with the examples when needed.
How It Works
Formula
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000Symbols are usually written from larger to smaller values, with subtraction patterns in specific cases such as IV and IX. The tool follows standard classroom-era formatting conventions.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Number to Roman numeral
Input Value49
ResultXLIX
Roman numeral to number
Input ValueMCMXCIV
Result1994
Common mistakes
- Writing IIII instead of IV
- Using invalid subtraction patterns such as IL for 49
- Repeating symbols too many times
- Mixing letters in a sequence that is not valid Roman numeral formatting
Frequently Asked Questions
Most Roman numeral converters support the standard range from 1 to 3999.
Yes. You can enter either a number or a Roman numeral and convert in the matching direction.
Standard Roman numeral formatting uses subtraction in cases like 4, 9, 40, 90, 400, and 900.
Usually yes. Most tools treat lowercase and uppercase the same, but output is generally shown in uppercase.
Not every sequence of Roman numeral letters is valid. The tool checks standard formatting rules, not just symbol values.
They still appear in clocks, book chapters, outlines, event names, and formal numbering.