How do you read Roman numerals?

Add up the values left to right. If a smaller value appears before a larger one, subtract it. For example, IV = 5-1 = 4, IX = 10-1 = 9, XL = 50-10 = 40.

Why does 4 become IV and not IIII?

The subtractive principle was introduced for compactness and readability. IIII is technically valid in some historical uses (clock faces still use IIII), but IV is the standard modern form.

Roman Numeral Converter — Numbers to Roman Numerals

Number → Roman Numeral

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Roman Numeral → Number

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Quick Reference

100

500

1000

What are Roman Numerals?

Roman numerals are a numeral system that originated in ancient Rome and remained the dominant writing system in Europe until the late Middle Ages. They use combinations of seven Latin letters to represent numbers: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000).

Roman numerals still appear today in clock faces, movie sequel numbering, Super Bowl titles, chapter headings, and year numbering on buildings and monuments. Understanding them connects us to thousands of years of cultural history.

How to Use

1To convert a number to Roman numerals: type any integer between 1 and 3,999 in the top box.
2To decode Roman numerals: type the Roman numeral in the bottom box (letters only).
3Results update instantly. Click Copy to copy to clipboard.

Formula

Number → Roman (greedy subtraction):
  Values: M=1000, CM=900, D=500, CD=400, C=100,
          XC=90, L=50, XL=40, X=10, IX=9, V=5, IV=4, I=1
  While N > 0: find largest value ≤ N,
    append its symbol, subtract value from N

Roman → Number (left-to-right with subtractive rule):
  If current value < next value → subtract current
  Else → add current
  Example: XIV = X(10) + I(1) + V(5) → 10−1+5 = ...
  Actually: X(10) + IV(4) = 14

Frequently Asked Questions

What are Roman numerals?

Roman numerals use letters from the Latin alphabet: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. When a smaller value precedes a larger one, it is subtracted (IV=4, IX=9, XL=40, XC=90, CD=400, CM=900).

What is the largest Roman numeral?

Using standard notation, the largest is MMMCMXCIX = 3,999. Beyond this, ancient Romans used vinculum (overline bars) to multiply values by 1,000, but this is rarely used today.

Why do clocks show IIII instead of IV?

IIII was the historical standard and predates the widespread use of the subtractive principle. Some theories say it provides visual symmetry on clock faces. Both IIII and IV are technically correct representations of 4.

Where are Roman numerals used today?

Roman numerals appear on clock faces, building cornerstones, movie sequels (Rocky IV), Super Bowl titles (Super Bowl LVIII), chapters in books, copyright dates in film credits, and names of monarchs and popes.

Roman Numeral Converter

What are Roman Numerals?

How to Use

Formula

Frequently Asked Questions

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