Roman Numeral Converter
Convert between Roman numerals and standard (Arabic) numbers instantly. Enter a number from 1 to 3,999 to get its Roman numeral form, or enter a Roman numeral symbol string to find its numeric value.
Result
Roman Numeral Reference Chart
| Symbol | Value | Notes |
|---|---|---|
| I | 1 | Basic unit |
| V | 5 | Five units |
| X | 10 | Ten units |
| L | 50 | Fifty units |
| C | 100 | One hundred (centum) |
| D | 500 | Five hundred |
| M | 1,000 | One thousand (mille) |
How Roman Numerals Work
Roman numerals use a system of additive and subtractive notation to represent numbers. Symbols are generally written from largest to smallest left to right, and their values are added. When a smaller symbol appears before a larger one, it is subtracted instead.
The six standard subtractive combinations are:
- IV = 4 (5 − 1)
- IX = 9 (10 − 1)
- XL = 40 (50 − 10)
- XC = 90 (100 − 10)
- CD = 400 (500 − 100)
- CM = 900 (1000 − 100)
So the year 2026 is written MMXXVI: MM (2000) + XX (20) + VI (6).
Rules for Writing Roman Numerals
- A symbol can be repeated at most three times in a row (e.g., III = 3, but IIII is nonstandard for 4; IV is correct).
- Only I, X, C, and M can be repeated. V, L, and D cannot be repeated.
- Only one small-value symbol can be subtracted at a time (e.g., IIX is not valid; 8 = VIII).
- The subtracting numeral can only be one step of magnitude smaller (I before V or X; X before L or C; C before D or M).
Where Are Roman Numerals Used Today?
You encounter Roman numerals more often than you might think:
- Clock faces — Traditional analog clocks often use Roman numerals. Our basic clock face generator includes Roman numeral options.
- Super Bowl and Olympics — Major events use Roman numerals to indicate which edition of the event it is (e.g., Super Bowl LVIII).
- Movie sequels and books — Copyright years in movie credits, volume numbers in books, and chapter headings often use Roman numerals.
- Outlines and legal documents — Roman numerals are standard for top-level headings in formal outlines and legal documents.
- Monarchs and popes — Names like King Charles III or Pope Francis use Roman numerals to indicate ordinal position.
Frequently Asked Questions
Why don't Roman numerals have a zero?
The Roman numeral system developed before the concept of zero was formalized in mathematics. Zero was later introduced from Indian mathematics via Arab scholars. The Latin word nulla ("none") was used informally, but no dedicated symbol existed in classical Roman notation.
What is the largest number in Roman numerals?
Using standard notation, the largest number is 3,999 (MMMCMXCIX). For numbers 4,000 and above, an overline or bar notation (indicating multiplication by 1,000) is sometimes used, but this isn't widely supported or standardized in modern typography.
Are Roman numerals still used officially?
Yes, in some contexts. The US Library of Congress uses them for copyright dates. Many legal documents and formal publications use them for outline numbering. They also appear in the names of laws and governmental bodies around the world.
