Roman Numerals Converter
Convert between numbers and Roman numerals. Numbers >3999 use a bar (vinculum) for ×1000. All in your browser.
Try it with this example
Enter 2024 to get MMXXIV. Or paste MCMXCIX and convert to 1999.
What is this tool?
Roman numerals use letters for values: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Numbers are formed by adding and subtracting: IV=4, IX=9, XL=40. The Roman Numerals Converter converts both ways. Enter 2024 and get MMXXIV. Enter MCMXCIX and get 1999. Useful for dates, outlines, copyright notices, and learning. Numbers over 3999 traditionally use a bar over the numeral for thousands; some tools use alternative notation.
Standard Roman numerals have no zero and no place value. Subtractive notation (IV instead of IIII for 4) was a later convention. The tool follows the common modern rules: I before V or X subtracts 1, X before L or C subtracts 10, C before D or M subtracts 100. Invalid input (e.g. IIII for 4 when IV is expected) may not parse correctly—the tool assumes well-formed Roman numerals when decoding.
Use it for copyright years (MMXXIV), book outlines (I, II, III, IV), clock faces, or when you encounter Roman numerals in a document and need the Arabic equivalent. Teachers use it for history and math lessons. The converter runs in your browser. No server, no API. Enter a number or Roman string and get the result.
For very large numbers, Roman notation becomes unwieldy. The tool typically supports at least 1–3999; extensions for 4000+ use a vinculum (bar) or parenthetical notation. Check the tool's documentation for exact range. For typical use—dates, outlines, decorative numbers—it covers the need.
Simple, educational, and always available.