Roman Numeral Converter

Convert between Roman numerals and Arabic (decimal) numbers in both directions.

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1. Choose the conversion direction: Roman to Arabic or Arabic to Roman. 2. For Roman to Arabic, enter a Roman numeral string like XIV or MCMLXXXIV. 3. For Arabic to Roman, enter any number between 1 and 3999. 4. View the converted result instantly with input validation. 5. Use the reference chart to learn Roman numeral values. 6. Click the copy button to copy the converted result.

About This Tool

The Roman Numeral Converter translates between Roman numeral notation and standard Arabic (decimal) numbers. Enter a Roman numeral like XIV and get 14, or enter a number like 2024 and get MMXXIV. The tool validates Roman numeral input for correct syntax and follows standard Roman numeral rules including subtractive notation.

Roman numerals remain in active use today - on clock faces, in movie and book numbering (Chapter IX, Super Bowl LVIII), on building cornerstones, in outlines and lists, and for copyright years. Being able to read and write Roman numerals is both practically useful and culturally relevant.

The converter handles numbers from 1 to 3,999 (the standard range for Roman numerals without extending the notation with bars or brackets). It validates input in both directions, catching common errors like IIII (should be IV) or invalid letter combinations. The tool also includes a reference table showing all the basic Roman numeral values and the subtractive notation rules.

Formula / How It Works

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

Frequently Asked Questions

The seven basic symbols are: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1000. All Roman numerals are built from combinations of these symbols.
When a smaller value appears before a larger one, it is subtracted. There are six subtractive pairs: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, and CM = 900. For example, 1994 = MCMXCIV (1000 + 900 + 90 + 4).
Using standard notation, the largest number is 3,999 (MMMCMXCIX). Beyond this, a vinculum (bar over letters) is sometimes used to multiply by 1,000, but this extended notation is uncommon in modern usage.
No. The Roman numeral system does not include a symbol for zero. It was developed before the concept of zero was widely adopted in Europe. The word "nulla" was sometimes used in medieval texts to represent zero.
Roman numerals are used for their visual distinction and traditional feel. Common modern uses include clock faces, Super Bowl numbering, movie sequel titles, book chapter headings, building dates, and formal outlines.

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