About this tool
Translate Roman numerals to integers and back, instantly and entirely in your browser. Type in either field and the other updates live.
Frequently asked questions
What range is supported?
Standard Roman numerals cover 1 to 3999, so values outside that range are rejected.
Does it reject invalid numerals?
Yes — it re-encodes your input and flags anything that is not a well-formed Roman numeral, like IIII or VX.