Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers, for values 1 to 3999.
Number → Roman numeral
Roman numeral → Number
How to use this tool
Type a number in the first box to see its Roman numeral, or type a Roman numeral in the second box to see its number. Both update live as you type.
About this conversion
Uses standard Roman numeral symbols (I=1, V=5, X=10, L=50, C=100, D=500, M=1000) with subtractive notation (IV=4, IX=9, XL=40, XC=90, CD=400, CM=900). Supports the standard range of 1 to 3999.
Frequently asked questions
What is the largest number that can be written in standard Roman numerals?
3999 (MMMCMXCIX), since standard notation has no single symbol for 5000 or higher and repeating M more than three times isn't used. Larger numbers require a special notation (like a bar over a numeral to multiply by 1000), which this tool doesn't support.
What is subtractive notation?
Placing a smaller symbol before a larger one to indicate subtraction, e.g. IV = 5 − 1 = 4, IX = 10 − 1 = 9, XL = 50 − 10 = 40. Only specific pairs are used (I before V/X, X before L/C, C before D/M) — not arbitrary combinations.