Math & Statistics
Roman Numeral Converter
Convert between regular numbers and Roman numerals instantly. Perfect for students, historians, and anyone working with Roman numeral systems.
What are Roman Numerals?
Roman numerals are a number system that originated in ancient Rome and were used throughout the Roman Empire for counting, trade, and record-keeping. Unlike our modern decimal system (0–9), Roman numerals use seven letters to represent values: I, V, X, L, C, D, and M.
Today, Roman numerals are still widely used in clock faces, book chapters, movie sequels (Rocky IV), monarch names (King Charles III), Super Bowl numbering (Super Bowl LVIII), and academic outlines. Understanding how to read and write them is a useful skill for students, historians, and everyday life.
How to Use This Converter
- Select the conversion direction
- Enter a number (1–3,999) or a Roman numeral
- Click Convert to see the result
- View the step-by-step breakdown and verification
Common Use Cases
- Reading clock faces
- Movie & event numbering
- History & royalty names
- Book chapters & outlines
- Copyright year dates
- School homework
How Roman Numerals Work
Addition Rule
When a smaller or equal numeral comes after a larger one, add them together.
- VI = 5 + 1 = 6
- XV = 10 + 5 = 15
- LXXX = 50 + 10 + 10 + 10 = 80
- MDCL = 1000 + 500 + 100 + 50 = 1650
Subtraction Rule
When a smaller numeral comes before a larger one, subtract the smaller from the larger.
- IV = 5 − 1 = 4
- IX = 10 − 1 = 9
- XL = 50 − 10 = 40
- XC = 100 − 10 = 90
- CD = 500 − 100 = 400
- CM = 1000 − 100 = 900
Complete Roman Numeral Reference Table
| Number | Roman | Number | Roman | Number | Roman | Number | Roman |
|---|---|---|---|---|---|---|---|
| 1 | I | 10 | X | 100 | C | 1000 | M |
| 2 | II | 20 | XX | 200 | CC | 1500 | MD |
| 3 | III | 30 | XXX | 300 | CCC | 1900 | MCM |
| 4 | IV | 40 | XL | 400 | CD | 2000 | MM |
| 5 | V | 50 | L | 500 | D | 2024 | MMXXIV |
| 6 | VI | 60 | LX | 600 | DC | 2025 | MMXXV |
| 7 | VII | 70 | LXX | 700 | DCC | 2500 | MMD |
| 8 | VIII | 80 | LXXX | 800 | DCCC | 3000 | MMM |
| 9 | IX | 90 | XC | 900 | CM | 3999 | MMMCMXCIX |
Common Roman Numerals in Everyday Life
Clock Faces
- I, II, III, IV (or IIII)
- V, VI, VII, VIII
- IX, X, XI, XII
Movies & Events
- Rocky IV = Rocky 4
- Star Wars Episode IX = 9
- Super Bowl LVIII = 58
Royalty & History
- King Charles III = 3rd
- Queen Elizabeth II = 2nd
- Louis XVI = 16th
FAQ – Roman Numeral Converter
What is a Roman Numeral Converter?
A Roman Numeral Converter helps you convert numbers between Roman numerals (I, V, X, L, C, D, M) and Arabic numbers (1, 2, 3, etc.). It's a quick tool to understand and use the ancient Roman numbering system.
How do Roman numerals work?
Roman numerals use combinations of seven letters — I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Numbers are formed by adding values when a smaller numeral follows a larger one (VI = 6), or subtracting when a smaller numeral precedes a larger one (IV = 4).
What is the largest number you can write in Roman numerals?
Using standard Roman numerals, the largest number is 3,999 (MMMCMXCIX). Numbers beyond that historically used overlines (a bar above a numeral multiplies it by 1,000), but these are not commonly used today.
Is there a Roman numeral for zero?
No. The Roman numeral system does not include a symbol for zero. The concept of zero was introduced later by Indian and Arabic mathematicians and was not part of the original Roman system.
What is 2025 in Roman numerals?
2025 = MMXXV. This breaks down as: MM (2000) + XX (20) + V (5).
Why do some clocks use IIII instead of IV?
Many clock faces use IIII instead of IV for the number 4. This is believed to be for visual balance — IIII on the left side mirrors VIII on the right side. It's also easier to read at a glance.
Can this tool convert both ways?
Yes! You can convert from numbers to Roman numerals (e.g., 42 → XLII) and from Roman numerals to numbers (e.g., XLII → 42). The tool also shows a step-by-step breakdown of the conversion.
Are Roman numerals still used today?
Yes. Roman numerals are used in clock faces, book chapters, movie sequels, monarch names, Super Bowl numbering, academic outlines, building cornerstones, and copyright dates on films and TV shows.
What are the subtraction rules in Roman numerals?
Only certain subtractions are allowed: I before V or X (IV=4, IX=9), X before L or C (XL=40, XC=90), and C before D or M (CD=400, CM=900). You cannot subtract other combinations like IL or XD.
How do I write years in Roman numerals?
Break the year into thousands, hundreds, tens, and ones, then convert each part. For example: 1999 = M (1000) + CM (900) + XC (90) + IX (9) = MCMXCIX.