Roman Numeral Converter
Convert any whole number from 1 to 3,999 into Roman numerals, or convert a Roman numeral back into its numeric value.
How the Roman Numeral Converter formula works
Roman numerals are built from seven symbols, combined additively and subtractively:
I=1 V=5 X=10 L=50 C=100 D=500 M=1000
Symbols are placed largest to smallest, subtracting when a smaller symbol precedes a larger one (like IV for 4, or IX for 9).
Step-by-step calculation
- Working from the largest value symbols down, repeatedly subtract the largest possible Roman numeral value from the number, appending its symbol each time.
- Special subtractive combinations (IV, IX, XL, XC, CD, CM) are used instead of repeating a symbol four times in a row.
Worked example
1994 breaks down as 1000 (M) + 900 (CM) + 90 (XC) + 4 (IV) = MCMXCIV.
Frequently asked questions
Why is 4 written as IV instead of IIII?
The subtractive principle (a smaller numeral before a larger one means subtraction) became the standard convention to avoid repeating a symbol more than three times in a row, though IIII does appear historically, especially on clock faces.
What's the largest number Roman numerals can represent?
With the standard seven symbols, 3,999 (MMMCMXCIX) is the largest value expressible without extending the notation — larger numbers historically used a bar over a numeral to multiply it by 1,000.