About Roman numerals
Roman numerals combine seven letters — I, V, X, L, C, D and M — using an additive and subtractive system, so 4 is written IV and 1994 is MCMXCIV. They still appear on clock faces, in book chapters, on monuments and in movie copyright years. This converter goes both ways across the standard 1–3999 range and validates Roman input, rejecting non-canonical forms like IIII. Everything runs locally in your browser.
Frequently asked questions
- How do I convert a number to a Roman numeral?
- Enter a whole number from 1 to 3999 — the Roman numeral appears instantly.
- What is the largest standard Roman numeral?
- 3999 (MMMCMXCIX); larger values need overlines outside the standard character set.
- Does it reject invalid numerals?
- Yes — non-standard forms such as IIII or VX are flagged as invalid.