Roman Numeral Converter

Convert between decimal numbers and Roman numerals. Supports 1 to 3,999.

Decimal → Roman

Roman → Decimal

📐 How We Calculate — Learn about our calculation methodology, data sources, and quality standards.

Roman Numeral Values

Symbol	Value	Symbol	Value
I	1	C	100
V	5	D	500
X	10	M	1,000
L	50

Subtractive Pairs

Combination	Value	Instead of
IV	4	IIII
IX	9	VIIII
XL	40	XXXX
XC	90	LXXXX
CD	400	CCCC
CM	900	DCCCC

Reading Years

2024 = MMXXIV: M(1000) + M(1000) + X(10) + X(10) + IV(4). 1994 = MCMXCIV: M(1000) + CM(900) + XC(90) + IV(4). The Super Bowl uses Roman numerals for each edition—Super Bowl LVIII was Super Bowl 58 in 2024.

Where You'll Still See Them

Clock faces (often IIII instead of IV by tradition), copyright dates on film credits, book chapter numbers, monarchs and popes (Henry VIII, Pope Benedict XVI), and annual events (Olympics, Super Bowls).

Frequently Asked Questions

How do Roman numerals work?

I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Place smaller before larger to subtract (IV=4, IX=9).

What is the largest Roman numeral?

Standard notation goes to 3,999 (MMMCMXCIX). A bar over a letter multiplies by 1,000 for larger numbers.

Why is 4 written as IV, not IIII?

IV (subtractive) is the modern standard, but IIII was also used in ancient Rome and appears on many clock faces.

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How to Use This Roman Numeral Converter

Enter a number (1-3999) to convert to Roman numerals, or enter Roman numerals to convert to Arabic numbers. The calculator validates the format.

Formula & How It Works

I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. Place larger values left.

Calculation Example

2024 = MMXXIV. 1999 = MCMXCIX (M+CM+XC+IX = 1000+900+90+9). 3999 = MMMCMXCIX (maximum representable value).

Expert Tips

Roman numerals are used in: outlines (I, II, III), clock faces, movie sequel numbering, Super Bowl numbers, and copyright years. The subtractive principle (IV instead of IIII) is standardized but historical usage varied.