Roman Numeral Converter
Converted ValueMMXXIV
Roman numerals build every value from seven letters — I, V, X, L, C, D, and M — combined under additive and subtractive rules. This converter translates a whole number from 1 to 3,999 into its Roman form and reads any valid Roman string back into a decimal number. It is handy for clock faces, book chapters, movie copyright years, and monument inscriptions.
Formula
Value uses M=1000, D=500, C=100, L=50, X=10, V=5, I=1 with the subtractive pairs CM=900, CD=400, XC=90, XL=40, IX=9, IV=4
- I
- One; may precede V or X to mean 4 or 9
- V
- Five
- X
- Ten; may precede L or C to mean 40 or 90
- L
- Fifty
- C
- One hundred; may precede D or M to mean 400 or 900
- D
- Five hundred
- M
- One thousand (largest single symbol; limits the range to 3,999)
How it works
- Pick a direction: "Number to Roman" accepts an integer from 1 to 3,999, while "Roman to Number" accepts a string of Roman letters (case-insensitive).
- Converting to Roman repeatedly subtracts the largest fitting value from the list M=1000, CM=900, D=500, CD=400, C=100, XC=90, L=50, XL=40, X=10, IX=9, V=5, IV=4, I=1, appending each numeral until nothing remains.
- Converting from Roman scans left to right, adding each letter unless it is smaller than the letter after it, in which case it is subtracted (for example IV = 5 − 1 = 4).
Worked examples
Write the year 2024 as a Roman numeral.
- 2024 − 1000 = 1024, append M, then again: 1024 − 1000 = 24, numeral so far MM.
- 24 fits X twice: 24 − 10 = 14, 14 − 10 = 4, numeral MMXX.
- 4 matches the subtractive pair IV, giving the final numeral.
2024 = MMXXIV
Read the Roman numeral MCMXCIV back into a number.
- M = 1000.
- CM is 100 before 1000, so it subtracts: 900, running total 1900.
- XC = 90 and IV = 4, giving 1900 + 90 + 4.
MCMXCIV = 1994
Frequently asked questions
- What is the largest number this converter supports?
- It converts whole numbers from 1 up to 3,999, written MMMCMXCIX. Classical Roman notation has no symbol above M, so values of 4,000 or more would need a bar (vinculum) notation that this tool does not use.
- Is there a Roman numeral for zero?
- No. The Roman system has no symbol for zero or for negative numbers, which is why conversion starts at 1. The concept of zero as a digit entered European mathematics much later through Hindu-Arabic numerals.
- Why is 4 written IV instead of IIII?
- The subtractive rule places a smaller symbol before a larger one to subtract it, so IV means five minus one. It keeps numerals short and avoids four identical letters in a row, though some clock faces still use IIII for tradition.
- Does capitalization matter when reading a Roman numeral?
- No. The converter uppercases your input before parsing, so "mcmxciv" and "MCMXCIV" both return 1994. Any character that is not one of I, V, X, L, C, D, or M is rejected as invalid.