Convert between Roman numerals and decimal numbers
Convert between Roman numerals and decimal numbers instantly. Includes a reference chart and common examples. This tool runs entirely in your browser — no data is sent to any server.
Roman numerals remain surprisingly relevant — they appear on clock faces, movie sequels (Rocky IV), Super Bowl numbering (Super Bowl LVIII), book chapters, building cornerstones, and formal outlines. The system uses seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), M (1000). Numbers are formed by combining symbols additively (VII = 7) and subtractively (IV = 4, IX = 9). This converter handles both directions instantly: enter 2024 and get MMXXIV, or enter MCMXCIX and get 1999. The standard system supports numbers from 1 to 3,999 — beyond that, Romans used overline notation (vinculum) which is rarely needed today.
Standard Roman numerals use M (1000) as the largest symbol. MMMCMXCIX (3999) is the maximum. Ancient Romans used vinculum — a bar over a symbol meaning ×1000 — for larger numbers, but this isn't widely supported in digital text.
Instead of writing IIII for 4, Romans wrote IV (5-1). Subtractive pairs: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. Only one smaller symbol can precede a larger one, and only specific combinations are valid.
Both have historical precedent. IV is standard in modern usage, but many clock faces use IIII — possibly for visual balance with VIII on the opposite side, or because IV was Jupiter's abbreviation (IVPITER) in ancient Rome.
Break the year into components: 2024 = 2000 + 20 + 4 = MM + XX + IV = MMXXIV. 1999 = 1000 + 900 + 90 + 9 = M + CM + XC + IX = MCMXCIX.
No — Roman numerals have no symbol for zero. The concept of zero came to Europe from India via Arab mathematicians centuries after the Roman Empire. This is why Roman numeral years start at 1, not 0.