Roman Numeral Converter
Free Roman numeral converter — convert numbers (1–3999) to Roman numerals and Roman numerals back to numbers, instantly in your browser.
Runs entirely in your browser — nothing you enter is uploaded or stored.
About the Roman Numeral Converter
Convert between ordinary numbers and Roman numerals in either direction. Roman numerals use seven letters — I, V, X, L, C, D, M — combined with subtractive notation, where a smaller value before a larger one is subtracted (for example IV is 4 and CM is 900).
The classical system represents whole numbers from 1 to 3999. The converter builds numerals with the standard greedy subtractive rules and validates any numeral you type, rejecting malformed or out-of-range values so you always get a correct result.
Frequently asked questions
What range is supported?
Standard Roman numerals cover 1 to 3999. Values outside that range have no standard form and are flagged as errors.
Does it work both ways?
Yes — type a number to get the numeral, or type a numeral to get the number. Whichever field you edit updates the other live.
Is the numeral input case-sensitive?
No. Lowercase or mixed case is accepted (e.g. "mcmxciv") and validated as a proper subtractive numeral.
Is this free & private?
Yes — free, no sign-up, runs entirely in your browser.