Convert numbers to Roman numerals, or Roman numerals back to numbers, instantly.
This tool converts numbers between standard Arabic numerals (1, 2, 3...) and Roman numerals (I, II, III...), the numbering system used in ancient Rome that still appears today in clock faces, book chapters, movie sequels, and formal document numbering.
Roman numerals use combinations of letters: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Numbers are formed by combining these symbols additively (like VI = 6) or subtractively when a smaller value precedes a larger one (like IV = 4, meaning 5−1).
Enter a number in either Arabic or Roman numeral format, and the converter instantly translates it to the other system.
Example 1: The number 1994 converts to Roman numerals as MCMXCIV.
Example 2: The Roman numeral XLII converts to 42 in Arabic numerals.
Why does IV mean 4 instead of writing IIII? Roman numerals use a subtractive principle where a smaller numeral placed before a larger one is subtracted, making IV (5−1=4) more compact than the additive IIII, though IIII does appear historically and on some clock faces for symmetry.
What is the largest number Roman numerals can typically represent? Standard Roman numerals go up to 3,999 (MMMCMXCIX) using the basic letter combinations; larger numbers historically used a bar over a numeral to indicate multiplication by 1,000.
Can Roman numerals represent zero? No, the Roman numeral system has no symbol for zero, since the concept of zero as a number wasn't part of Roman mathematics — zero developed separately in Indian and later Arabic mathematical traditions.
Where are Roman numerals still commonly used today? Common modern uses include clock and watch faces, book and document chapter numbering, movie sequel titles, Super Bowl numbering, and formal event or edition numbering.
Why do some clocks show IIII instead of IV for the number 4? This is a stylistic and historical convention on many clock faces, sometimes attributed to visual balance with the VIII on the opposite side, though the exact historical reason is debated among clockmakers and historians.