Roman Numeral Converter
Quickly convert any number between 1 and 3,999 to its Roman numeral equivalent, or convert a calendar date into the elegant Roman format.
How do Roman numerals work?
Roman numerals use seven letters: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Rules: 1) Add when larger/equal comes before smaller (VI=6). 2) Subtract when smaller comes before larger (IV=4). 3) Only subtract powers of 10 (I, X, C). 4) Never subtract more than one numeral or repeat subtraction (99=XCIX not IC).
Why is 4 written as IV and not IIII?
Subtractive notation (IV) became standard in medieval times for efficiency, though IIII appears on some clock faces for symmetry/tradition. Rules: I before V or X (4=IV, 9=IX), X before L or C (40=XL, 90=XC), C before D or M (400=CD, 900=CM).
How do I write a date in Roman numerals?
To write a date, you convert the day, month, and year separately. For example, for the date 05/12/2024: Day 5 is V, Month 12 is XII, and Year 2024 is MMXXIV. The full Roman date would be V.XII.MMXXIV or V-XII-MMXXIV.
What is the largest number in Roman numerals?
Standard Roman numerals go to 3,999 (MMMCMXCIX). Ancient Romans used vinculum (overline) for larger numbers, but without it, the modern standard limits at 3,999 because you cannot repeat M more than three times.