How to Read and Write Roman Numerals
Roman numerals use seven symbols to represent numbers. They originated in ancient Rome and are still used in certain contexts today, such as clock faces, book chapters, movie credits, and major events like the Super Bowl and Olympics.
The Seven Base Symbols
| Symbol | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Value | 1 | 5 | 10 | 50 | 100 | 500 | 1,000 |
Rules for Writing Roman Numerals
- Additive rule: When numerals are in descending order (left to right), add their values.
VII = 5 + 1 + 1 = 7 - Subtractive rule: When a smaller numeral precedes a larger one, subtract the smaller value.
IV = 5 − 1 = 4,IX = 10 − 1 = 9 - Repetition limit: A symbol can be repeated up to 3 times consecutively. Use subtractive notation instead of four repetitions:
IVnotIIII. - Only certain subtractive pairs exist: I before V or X; X before L or C; C before D or M.
Examples
| Arabic | Roman | Breakdown |
|---|---|---|
| 3 | III | 1 + 1 + 1 |
| 14 | XIV | 10 + (5 − 1) |
| 49 | XLIX | (50 − 10) + (10 − 1) |
| 399 | CCCXCIX | 100 + 100 + 100 + (100 − 10) + (10 − 1) |
| 1994 | MCMXCIV | 1000 + (1000 − 100) + (100 − 10) + (5 − 1) |
| 2025 | MMXXV | 1000 + 1000 + 10 + 10 + 5 |
Date Conversion
To convert a date, enter each part (year, month, day) separated by -, ., /, \, |, or a space. Each part is converted independently. For example, 2025/03/19 becomes MMXXV/III/XIX.
History of Roman Numerals
Roman numerals were widely used throughout the Roman Empire and continued in common use across Europe well after its fall. Arabic numerals (the 0–9 system we use today) began replacing them around the 14th century, primarily because arithmetic operations are much easier with a positional number system that includes zero.
Despite this, Roman numerals persist in many formal and traditional contexts, valued for their distinctiveness and aesthetic quality.