About the Roman Numeral Converter
Roman numerals are a numeral system originating in ancient Rome, still used today for clock faces, book chapters, movie sequels, and formal numbering. The system uses seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), M (1000). Our converter handles bidirectional conversion between Roman and decimal notation for values from 1 to 3,999.
How Roman numerals work
Symbols are generally written from largest to smallest, left to right, and their values are added together. When a smaller symbol appears before a larger one, it is subtracted instead — for example, IV = 4 (5 − 1) and XC = 90 (100 − 10). Only I, X, and C can be used as subtractive prefixes.
Why 1–3,999?
Standard Roman numeral notation cannot represent zero or numbers above 3,999 without extending the system (e.g., using a vinculum or parentheses for multiplication by 1,000). Our converter sticks to the classical range to ensure correct, unambiguous results. All processing runs entirely in your browser.