Roman Numeral Converter
Convert ordinary numbers into standard Roman numerals and validate Roman numerals by converting them back into integers. The converter supports the traditional range from 1 through 3999 and rejects non-standard numeral sequences.
Number to Roman numeral
Roman numeral to number
This converter validates standard Roman numeral notation from I through MMMCMXCIX.
How to use the Roman Numeral Converter
- Enter a whole number from 1 through 3999 to convert it to Roman notation.
- The converter selects the largest Roman value that fits and continues until the number is represented.
- Subtractive forms such as IV, IX, XL, XC, CD and CM are supported.
- For reverse conversion, enter a Roman numeral.
- The tool converts it back and verifies that the numeral matches the standard canonical representation.
Examples
2026
2026 converts to MMXXVI.
1999
1999 converts to MCMXCIX.
IX
IX converts to 9 using subtractive notation.
Frequently asked questions
Is there a Roman numeral for zero?
Classical Roman numeral notation has no standard numeral for zero.
Why is 4 written IV?
IV uses subtractive notation: one before five means five minus one.
What is the largest number supported?
This calculator uses the common modern standard from 1 through 3999.
Does the converter validate Roman numerals?
Yes. Reverse conversions must match the standard canonical Roman numeral form.
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