Roman Numeral Rules
Roman numerals use seven symbols to represent numbers. Understanding these symbols and the rules for combining them is essential for reading and writing Roman numerals correctly.
The 7 Basic Symbols
| Symbol | Value | Origin |
|---|---|---|
| I | 1 | One finger |
| V | 5 | Open hand (V-shape) |
| X | 10 | Two crossed hands |
| L | 50 | Half of C (rotated) |
| C | 100 | Centum (Latin for 100) |
| D | 500 | Half of M (halved) |
| M | 1,000 | Mille (Latin for 1000) |
5 Writing Rules
Rule 1: Addition Principle
When a symbol of equal or greater value precedes another, add their values. Example: VI = 5 + 1 = 6, XV = 10 + 5 = 15.
Rule 2: Subtraction Principle
When a smaller symbol appears before a larger one, subtract the smaller from the larger. Only six subtractive pairs are valid: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).
Rule 3: Repetition Limit
I, X, C, and M may be repeated up to 3 times in succession. Example: III = 3, XXX = 30. But IIII is invalid; use IV = 4 instead.
Rule 4: No Repetition of V, L, D
The symbols V (5), L (50), and D (500) can never be repeated. VV is wrong; use X = 10 instead. LL is wrong; use C = 100 instead.
Rule 5: Largest to Smallest (Left to Right)
Roman numerals are written from the largest value on the left to the smallest on the right, except when using the subtraction principle. Example: MCMLXXXIV = 1984 (M=1000, CM=900, LXXX=80, IV=4).
How to Convert Number to Roman Numeral
Follow these steps to convert any number between 1 and 3,999 to its Roman numeral equivalent.
Step 1: Know the reference values
Memorize the 13 key values: M(1000), CM(900), D(500), CD(400), C(100), XC(90), L(50), XL(40), X(10), IX(9), V(5), IV(4), I(1).
Step 2: Find the largest value that fits
Starting from the largest (M=1000), find the biggest value that does not exceed your number.
Step 3: Write the symbol and subtract
Write down that Roman numeral symbol and subtract its value from your number.
Step 4: Repeat until zero
Continue finding the largest fitting value, writing it down, and subtracting until the remaining number is 0.
Example: Convert 1984 to Roman Numerals
1. 1984 ≥ 1000 → write M, remaining: 984
2. 984 ≥ 900 → write CM, remaining: 84
3. 84 ≥ 50 → write L, remaining: 34
4. 34 ≥ 10 → write X, remaining: 24
5. 24 ≥ 10 → write X, remaining: 14
6. 14 ≥ 10 → write X, remaining: 4
7. 4 ≥ 4 → write IV, remaining: 0
Result: 1984 = MCMLXXXIV
How to Convert Roman Numeral to Number
To read a Roman numeral, scan from left to right and apply the addition and subtraction principles.
Step 1: Start from the left
Look at each symbol from left to right.
Step 2: Compare consecutive symbols
If the current symbol is smaller than the next one, subtract it. Otherwise, add it.
Step 3: Sum all values
Keep a running total until you reach the end of the Roman numeral string.
Example: Convert MCMXCIV to a Number
1. M = 1000 (add, because M ≥ C)
2. C = 100 (subtract, because C < M next) → −100
3. M = 1000 (add) → +1000
4. X = 10 (subtract, because X < C next) → −10
5. C = 100 (add) → +100
6. I = 1 (subtract, because I < V next) → −1
7. V = 5 (add, last symbol) → +5
Total: 1000 − 100 + 1000 − 10 + 100 − 1 + 5 = 1994
Roman Numerals Chart 1–100
This reference table shows every Roman numeral from 1 to 100. The first 20 values are shown by default; expand to see all 100.
| Number | Roman | Number | Roman | Number | Roman | Number | Roman |
|---|---|---|---|---|---|---|---|
| 1 | I | 6 | VI | 11 | XI | 16 | XVI |
| 2 | II | 7 | VII | 12 | XII | 17 | XVII |
| 3 | III | 8 | VIII | 13 | XIII | 18 | XVIII |
| 4 | IV | 9 | IX | 14 | XIV | 19 | XIX |
| 5 | V | 10 | X | 15 | XV | 20 | XX |
Common Year Conversions
Here are the Roman numeral representations for recent and notable years:
| Year | Roman Numeral |
|---|---|
| 2020 | MMXX |
| 2021 | MMXXI |
| 2022 | MMXXII |
| 2023 | MMXXIII |
| 2024 | MMXXIV |
| 2025 | MMXXV |
| 2026 | MMXXVI |
| 2027 | MMXXVII |
| 2028 | MMXXVIII |
| 2029 | MMXXIX |
| 2030 | MMXXX |
Where Roman Numerals Are Used Today
- Clock and watch faces — Traditional analog clocks use Roman numerals for the hour markers (I through XII), with IIII sometimes used instead of IV for aesthetic balance.
- Super Bowl numbering — The NFL names each Super Bowl with Roman numerals (e.g., Super Bowl LVIII = 58). This tradition started with Super Bowl V in 1971.
- Movie sequels and series — Film franchises often use Roman numerals for sequels: Rocky II, Star Wars Episode IV, The Godfather Part III.
- Building cornerstones and monuments — Dates carved in stone on buildings, memorials, and institutions are traditionally written in Roman numerals (e.g., MCMXLV = 1945).
- Papal names — Popes use Roman numerals to distinguish themselves from predecessors with the same name: Pope John Paul II, Pope Benedict XVI, Pope Francis (I).
- Book chapters and outlines — Roman numerals are used for major divisions, front matter page numbers, and formal outlines (I, II, III...).
- Tattoos and jewelry — Dates in Roman numerals are popular choices for commemorative tattoos and engraved jewelry, especially birth dates, wedding dates, and anniversaries.
- Copyright dates — Film and television credits sometimes display the copyright year in Roman numerals (e.g., MMXXVI for productions in 2026).
Related Converters
Explore our other number system converters and tools:
- Caesar Cipher — Named after Julius Caesar, who used a shift cipher for military communication in ancient Rome
- Number to Words Converter — Convert numbers to their English word representation
- Binary to Decimal Converter — Convert binary numbers to decimal values
- Date Calculator — Calculate days between dates and add or subtract days from a date
For a deep dive into Roman numeral history and complete reference charts, read our comprehensive guide: Roman Numerals Chart: Complete List from 1 to 1000 with Rules.