About the Roman Numeral Converter
Turn any whole number into Roman numerals, or type a Roman numeral to read its value. Both fields update as you type, and a breakdown shows how the numeral is built, for example 1994 = M + CM + XC + IV.
Numbers from 4,000 to 3,999,999 use the vinculum: a bar over symbols multiplies them by 1,000. Roman input is checked strictly, so invalid forms such as IIII or IC are flagged with an explanation and the correct spelling.
How to use the Roman Numeral Converter
- Type a value in “Number” to get its Roman numeral, or in “Roman numeral” to get its value.
- For 4,000 and above, type the barred part in parentheses, for example (IV)CD for 4,400.
- Read the result and the breakdown under “How it is built”, and copy the numeral if you need it.
- Use the symbol table as a quick reference; click a row to convert it.
Frequently asked questions
What are the rules for writing Roman numerals?
Symbols are written from largest to smallest and added up. To write 4s and 9s, a smaller symbol goes before a larger one and is subtracted: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. I, X, C and M can repeat up to three times in a row; V, L and D never repeat.
How do you write numbers above 3,999?
A bar (vinculum) over symbols multiplies them by 1,000. So V̅ = 5,000, X̅ = 10,000 and M̅ = 1,000,000. For example, 4,400 is I̅V̅CD and the largest supported number, 3,999,999, is M̅M̅M̅C̅M̅X̅C̅I̅X̅CMXCIX.
Why is IIII not accepted?
Standard form never repeats a symbol four times; 4 is written IV. IIII appears on some clock faces, but it is not the standard spelling, so the converter suggests IV instead.
Is there a Roman numeral for zero?
No. The Roman system had no symbol for zero or for negative numbers, so the converter starts at 1.