Roman Numeral Converter

Convert between Roman numerals and Arabic numbers instantly. Free Roman numeral converter for history homework, ancient studies, and educational projects.

Smart Tips

• Basic Roman numerals: I=1, V=5, X=10, L=50, C=100, D=500, M=1000

• Subtractive notation: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900

• Roman numerals are commonly used for clock faces, movie sequels, and formal documents

• The largest standard Roman numeral is 3,999 (MMMCMXCIX)

The Formula

Rule	Description
Addition	Add values when a larger numeral follows a smaller one (VI = 5 + 1 = 6)
Subtraction	Subtract when a smaller numeral precedes a larger one (IV = 5 - 1 = 4)
Symbols	I=1, V=5, X=10, L=50, C=100, D=500, M=1000

Roman Numerals Reference

Roman Numeral	Value	Description
I	1	Basic unit, can repeat up to 3 times
V	5	Half of X, cannot be repeated
X	10	Base 10 unit, can repeat up to 3 times
L	50	Half of C, cannot be repeated
C	100	Century marker, can repeat up to 3 times
D	500	Half of M, cannot be repeated
M	1000	Millennium marker, can repeat up to 3 times

Key Insights

Basic Symbols

Roman numerals use I (1), V (5), X (10), L (50), C (100), D (500), and M (1000) as fundamental symbols.

Subtraction Rule

When a smaller numeral appears before a larger one, subtract it (e.g., IV = 4, IX = 9, XL = 40).

Addition Rule

When numerals are in descending order, add them (e.g., VI = 6, XII = 12, LV = 55).

Modern Uses

Roman numerals are still used for book chapters, movie sequels, clock faces, and formal document numbering.

Frequently Asked Questions

Roman numerals use letters to represent numbers: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Numbers are formed by combining these letters, with special rules for subtraction (IV=4, IX=9).

Subtraction occurs when a smaller numeral appears before a larger one: IV=4 (5-1), IX=9 (10-1), XL=40 (50-10), XC=90 (100-10), CD=400 (500-100), CM=900 (1000-100).

Read from left to right, adding values unless a smaller numeral precedes a larger one (then subtract). Our converter handles this automatically and provides accurate conversions.

Theoretically unlimited, but practically limited by readability. Large numbers use overlines (M̄ = 1,000,000) or parentheses. Our converter handles standard Roman numerals up to 3,999 (MMMCMXCIX).

Roman numerals are used in clock faces, book chapters, movie credits, monarch names, and formal documents. They're also common in academic and historical contexts.

Our Roman numeral conversions are based on the classical Roman numeral system, subtractive notation principles, and historical numbering conventions.

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Converted Value

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Note: Roman numeral conversions follow classical rules with additive and subtractive notation. For historical documents, verify the notation style used to ensure accurate interpretation.