Math
Roman Numeral Converter
Convert any number between Arabic and Roman notation, from I to MMMCMXCIX (1–3,999). The converter detects the input type automatically.
The converter detects the input type automatically
Quick examples
Arabic → Roman
Frequently asked questions
What is the largest number I can convert?
Standard Roman numerals only go up to 3,999 (MMMCMXCIX). Numbers above that historically used overlines, which we do not support.
Why is 4 written as IV and not IIII?
Modern subtractive notation uses IV for 4 and IX for 9. Older clocks sometimes still use IIII for stylistic reasons, but IV is the standard.
Does it accept lowercase Roman letters?
Yes — the converter normalizes input to uppercase, so iv and IV both work.