Roman Numeral Converter: Numbers the Roman Way
Roman numerals use letters for values and subtraction for 4s and 9s. Once you know the pairs — IV, IX, XL, XC, CD, CM — any number up to 3999 converts cleanly.
What is the Roman Numeral Converter?
Choose a direction and enter a value. To Roman numerals, the tool builds the numeral with standard subtractive notation, so 4 is IV and 9 is IX, not IIII or VIIII. From Roman numerals, it reads the numeral back, handling subtractive pairs correctly.
How to use it
- Choose a conversion direction.
- Enter a number or a Roman numeral.
- Click Convert for the converted value.
Worked example
The number 2026 converts to MMXXVI: 2000 as MM, 20 as XX, and 6 as VI.
Why is 4 written IV and not IIII?
Because Roman numerals use subtractive notation: a smaller value before a larger one is subtracted, so IV means 5 minus 1.
Frequently asked questions
What is the largest number this tool handles?
3999, written MMMCMXCIX. Roman numerals have no standard zero or values beyond that in this converter.
Does it accept lowercase numerals?
Yes. Lowercase Roman numerals are converted to uppercase before reading.