Roman numerals are built from seven letters: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000. You read them left to right, adding as you go, except when a smaller symbol sits before a larger one, when you subtract it (so IV = 4, IX = 9).
Roman numerals are still all around us: on clock faces, book chapters, the Super Bowl, film copyright dates, and the cornerstones of buildings. They also happen to be the numbers we mark our daily facts with. Here is how the whole system works, with a full chart you can copy.
The seven symbols
- I1
- V5
- X10
- L50
- C100
- D500
- M1000
That is the entire alphabet of the system. Every Roman number, from 1 to the thousands, is spelled out of these seven letters.
The two rules
1. Add when symbols go from large to small. Line the symbols up from biggest to smallest and add their values. VI is 5 + 1 = 6. XVII is 10 + 5 + 1 + 1 = 17. MDCLXVI is 1,000 + 500 + 100 + 50 + 10 + 5 + 1 = 1,666.
2. Subtract when a smaller symbol comes first. To avoid writing four of the same letter in a row, Romans put a smaller symbol before a larger one to mean "subtract." IV is 5 − 1 = 4. IX is 10 − 1 = 9. Only six subtractive pairs are used:
| Numeral | Value | Means |
|---|---|---|
| IV | 4 | 5 − 1 |
| IX | 9 | 10 − 1 |
| XL | 40 | 50 − 10 |
| XC | 90 | 100 − 10 |
| CD | 400 | 500 − 100 |
| CM | 900 | 1,000 − 100 |
How to read any numeral
Work from left to right. If a symbol is followed by one of equal or smaller value, add it. If it is followed by a larger value, subtract it instead. Take MCMXCIV:
- M = 1,000
- CM = 900
- XC = 90
- IV = 4
Add those up: 1,000 + 900 + 90 + 4 = 1994.
Roman numerals chart: 1 to 20
| Number | Roman | Number | Roman |
|---|---|---|---|
| 1 | I | 11 | XI |
| 2 | II | 12 | XII |
| 3 | III | 13 | XIII |
| 4 | IV | 14 | XIV |
| 5 | V | 15 | XV |
| 6 | VI | 16 | XVI |
| 7 | VII | 17 | XVII |
| 8 | VIII | 18 | XVIII |
| 9 | IX | 19 | XIX |
| 10 | X | 20 | XX |
Tens, hundreds, and thousands
| Value | Roman | Value | Roman |
|---|---|---|---|
| 10 | X | 100 | C |
| 20 | XX | 200 | CC |
| 30 | XXX | 300 | CCC |
| 40 | XL | 400 | CD |
| 50 | L | 500 | D |
| 60 | LX | 600 | DC |
| 70 | LXX | 700 | DCC |
| 80 | LXXX | 800 | DCCC |
| 90 | XC | 900 | CM |
| 100 | C | 1,000 | M |
Writing years in Roman numerals
To convert a big number, break it into thousands, hundreds, tens, and ones, then spell each part and join them together. A few worked examples:
| Year | Roman numeral | Broken down |
|---|---|---|
| 2026 | MMXXVI | MM + XX + V + I |
| 2000 | MM | 1,000 + 1,000 |
| 1984 | MCMLXXXIV | M + CM + LXXX + IV |
| 1776 | MDCCLXXVI | M + DCC + LXX + VI |
| 476 | CDLXXVI | CD + LXX + VI |
Common mistakes to avoid
- There is no zero. The system has no symbol for it, and no need for one.
- Don't repeat a symbol four times. Write IV, not IIII; XL, not XXXX. (The one famous exception is clock faces, which often use IIII for 4 by old tradition.)
- Only I, X, and C are used to subtract. You will see IV, IX, XL, XC, CD, and CM, but never things like IL or IC.
- Order matters. VI is 6, but IV is 4. Same letters, different meaning.
Why Rome had no zero
Roman numerals were a tool for recording and counting, not for calculation, so a placeholder for "nothing" was never built in. Romans did arithmetic on a counting board or abacus and only wrote the result down. Zero as a true number reached Europe much later, through Arabic numerals, the 0–9 digits we use today. It is one small reason the system stuck around for symbols and dates but was replaced for actual math.
Sources: standard references on the Roman numeral system and the history of numerals. The "no four-in-a-row" convention and the six subtractive pairs describe modern standard usage; ancient inscriptions were sometimes less consistent.
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