Turn numbers into Roman numerals, and back.
Convert a number into a Roman numeral, or read a Roman numeral back into a number. Standard subtractive notation, full validation, and a live breakdown of every symbol.
Convert
I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive pairs: IV, IX, XL, XC, CD, CM.
What this means
Breakdown
| Symbol | Value | Meaning |
|---|
How Roman numerals work
How Roman Numerals Work
Roman numerals use seven symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Numbers are formed by combining symbols. When a smaller symbol precedes a larger one, it is subtracted (IV=4, IX=9). Otherwise, values are added (VI=6, XI=11).
Subtractive Notation
Six subtractive combinations are used: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. For example, 2024 = MMXXIV (1000+1000+10+10+4). This notation keeps numerals shorter and was standardized in the Middle Ages.
Modern Uses of Roman Numerals
Roman numerals are used for clock faces, Super Bowl numbers, movie sequels, book chapters, outlines, building cornerstones, monarch names (Queen Elizabeth II), and copyright dates. They add a classical or formal appearance to text.
Limitations of Roman Numerals
Standard Roman numerals cannot represent zero or negative numbers. The largest standard numeral is 3,999 (MMMCMXCIX). For larger numbers, a vinculum (bar over the numeral) multiplies the value by 1,000, but this system is rarely used.
Common questions
What is the largest number in Roman numerals?
Using standard notation, the largest number is 3,999 (MMMCMXCIX). The bar notation (vinculum) can extend this by placing a line over a numeral to multiply by 1,000, but this is rarely used in modern contexts.
Why is 4 written as IV instead of IIII?
Subtractive notation (IV) is the standard modern convention. However, IIII is also seen, particularly on clock faces, where IIII is preferred for visual balance with VIII on the opposite side. Both forms are technically valid.
How do you write zero in Roman numerals?
There is no Roman numeral for zero. The concept of zero was not part of Roman mathematics. The word "nulla" (meaning nothing) was sometimes used in medieval texts where zero was needed.
What year is MMXXIV?
MMXXIV is 2024. MM = 2000, XX = 20, IV = 4. This is a common example since it represents a recent year. Similarly, MMXXV = 2025 and MMXXVI = 2026.
Standard Roman numerals run from 1 to 3,999 and have no symbol for zero or negative numbers.