Roman Numeral Converter
Convert a number between 1 and 3999 into Roman numerals.
How Roman numerals work
Roman numerals use combinations of letters (I, V, X, L, C, D, M) representing fixed values, with smaller values placed before larger ones to indicate subtraction (like IV for 4).
Where Roman numerals still appear today
Roman numerals remain common in specific contexts: clock faces, book chapter numbering, movie sequel and Super Bowl numbering, monarch and pope naming conventions (like Elizabeth II), and formal document dating.
Understanding the subtractive notation (like IV for 4, meaning 'one less than five') is key to reading Roman numerals correctly — a smaller numeral placed before a larger one indicates subtraction, while one placed after indicates addition.
A worked example
2026 converts to MMXXVI: 2000 equals MM, 20 equals XX, 6 equals VI, combined as MMXXVI.
1994 converts to MCMXCIV: 1000 equals M, 900 equals CM (subtractive), 90 equals XC (subtractive), 4 equals IV (subtractive) — a good example of how subtractive notation appears multiple times in a single number.
Roman numeral rules explained
Roman numerals follow an additive and subtractive system: symbols are generally added left to right (VI = 5+1 = 6), but when a smaller value precedes a larger one, it's subtracted instead (IV = 5−1 = 4). No symbol is repeated more than three times in a row, which is why 4 is IV rather than IIII.
Roman numerals are still commonly used today for stylistic purposes — clock faces, book chapter numbering, movie sequel titles, monarch and Super Bowl numbering, and formal document dating all frequently use this ancient number system.
Frequently asked questions
Why is there a limit of 3999?
Standard Roman numerals don't have a symbol for numbers of 4,000 or more without special notation (like an overline), so 3999 (MMMCMXCIX) is the largest number expressible with standard letters.
Why is 4 written as IV instead of IIII?
Modern convention uses subtractive notation (IV = 5 minus 1) for cleaner, shorter numerals, though IIII does appear historically and is still sometimes used on clock faces for symmetry.
How do I write very large numbers in Roman numerals?
Standard notation without special marks tops out at 3,999 (MMMCMXCIX) — larger numbers historically used an overline to multiply a numeral's value by 1,000, though this isn't standardized in modern digital text.
Why is 4 written as IV instead of IIII?
Roman numeral convention avoids repeating a symbol more than three times in a row, so the subtractive form (I before V) is used instead — this rule became standard, though ancient Romans didn't apply it perfectly consistently.