Number & Math
Roman Numeral Converter
Convert between Arabic numbers (1-3999) and Roman numerals.
Arabic number (1-3999)
Roman numeral
Breakdown
About this tool
Type a Roman numeral (I, V, X, L, C, D, M) or an Arabic number 1-3999. The converter validates and translates in either direction. Accepts both subtractive (IV = 4) and additive (IIII = 4) forms on input; outputs the standard subtractive form by default.
FAQs
What's the maximum number?
3999 (MMMCMXCIX). Beyond that the standard subtractive notation runs out of letters. Some traditions use overlines or extra letters for higher values; this tool keeps it standard.
Is there a Roman zero?
No - the Romans had no digit for zero. Medieval scholars used the word 'nulla' or N. Modern texts sometimes show 0 as a placeholder, but it isn't classical.
Why is 4 'IV' and not 'IIII'?
Subtractive notation became standard in the Middle Ages. You'll still see IIII on clock faces - traditionally to balance VIII visually opposite, or because IV was associated with the god Jupiter (IVPITER).
Are lowercase numerals supported?
Yes - i, v, x, etc. are accepted on input and treated identically. Output is uppercase by default; a toggle switches to lowercase.
Can I convert years like 1999?
Yes - 1999 is MCMXCIX (M = 1000, CM = 900, XC = 90, IX = 9). The tool shows the breakdown so you can see how the subtraction rule applies.