Last updated: April 2026
The Roman Numeral Converter translates between Roman numerals and decimal numbers in both directions. Type a number from 1 to 3999 and get the Roman numeral equivalent, or type a Roman numeral and see the decimal value. The tool works bidirectionally with real-time updates as you type. A built-in reference chart shows all Roman numeral symbols and their values for quick lookup. This is perfect for students studying history or math, writers formatting outlines and chapter numbers, event planners working with dates (like Super Bowl numbering), and anyone who encounters Roman numerals in clocks, buildings, or documents. The tool validates your input and handles subtractive notation (like IV for 4 and IX for 9) correctly.
Type any number from 1 to 3999 in the Decimal Number field. The Roman numeral equivalent appears instantly in the Roman Numeral field next to it.
Type Roman numerals (I, V, X, L, C, D, M) in the Roman Numeral field. The decimal value updates automatically as you type. Both uppercase and lowercase letters are accepted.
Scroll down to the Quick Reference section to see all 13 Roman numeral values including subtractive combinations like IV (4), IX (9), XL (40), and CM (900).
Click the copy button between the two values to copy the full conversion (for example '2024 = MMXXIV') to your clipboard.
Roman Numeral Converter is the fastest way to convert between Roman and decimal numbers online. Key advantages include bidirectional conversion, real-time updates, and a built-in reference chart.
The seven basic Roman numeral symbols are: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). All Roman numerals are written using combinations of these symbols, either by adding them together (III = 3) or using subtractive notation where a smaller symbol before a larger one means subtraction (IV = 4).
Subtractive notation places a smaller symbol before a larger one to indicate subtraction. The six subtractive combinations are: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900). This notation exists to avoid four repeated symbols, so 4 is written as IV instead of IIII. However, on many clock faces, you will see IIII used for 4, which is an accepted tradition.
Standard Roman numeral notation can only represent numbers up to 3999 (MMMCMXCIX). To write 4000, you would need four M's in a row, which violates the rule of not using the same symbol more than three times consecutively. Extended Roman numeral systems use bars over letters to represent multiplication by 1000, but the standard system used in everyday contexts is limited to 3999.
MMXXIV is 2024 in decimal. Breaking it down: MM = 2000, XX = 20, IV = 4. Together, 2000 + 20 + 4 = 2024. Roman numerals are commonly used for years in movie credits, building cornerstones, Super Bowl numbering, and formal documents.
Roman numerals are still used in many places: clock and watch faces, Super Bowl numbering (Super Bowl LVIII), movie sequel titles, book chapter numbering, outlines and lists, monarch names (King Charles III), building construction dates, copyright years in film credits, and academic paper sections. Understanding them remains a practical skill.