A Complete Guide to Roman Numerals
March 30, 2026
What Are Roman Numerals?
Roman numerals are a number system from ancient Rome that uses combinations of seven Latin letters to represent values. Unlike our modern system (0-9 with place value), Roman numerals use additive and subtractive rules to build numbers from these symbols.
They were the standard across Europe for over a thousand years. Today they're decorative rather than functional, but they still show up everywhere — and understanding them takes about five minutes.
The Seven Symbols
| Symbol | Value | Origin |
|---|---|---|
| I | 1 | A single tally mark — one finger held up |
| V | 5 | An open hand, all five fingers spread |
| X | 10 | Two hands crossed (or two V shapes joined) |
| L | 50 | Evolved from an Etruscan symbol, reshaped into a Latin letter |
| C | 100 | From centum (Latin for hundred) |
| D | 500 | Half of the ancient symbol for 1,000 |
| M | 1,000 | From mille (Latin for thousand) |
These seven symbols can represent any number from 1 to 3,999 in standard notation.
The Four Rules
1. Addition: bigger comes first
When symbols go from large to small (left to right), you add them up:
- VI = 5 + 1 = 6
- LXIII = 50 + 10 + 1 + 1 + 1 = 63
- MDCLXVI = 1000 + 500 + 100 + 50 + 10 + 5 + 1 = 1,666
2. Subtraction: smaller before bigger
When a smaller symbol appears directly before a larger one, subtract it:
- IV = 5 − 1 = 4
- IX = 10 − 1 = 9
- XL = 50 − 10 = 40
- XC = 100 − 10 = 90
- CD = 500 − 100 = 400
- CM = 1000 − 100 = 900
Only these six subtractive pairs are valid. You can't write things like IC (99) or XM (990).
3. Maximum three in a row
You can repeat I, X, C, and M up to three times. Never four. That's why 4 is IV (not IIII) and 40 is XL (not XXXX).
V, L, and D are never repeated — doubling them would just equal the next symbol up (VV = X).
4. Read left to right
Process the numeral from left to right, applying addition and subtraction as you go. When you spot a smaller value before a larger one, subtract. Otherwise, add.
Converting Numbers to Roman Numerals
Break the number down by place value, convert each part, then concatenate:
Example: 1,994
| Place | Value | Roman |
|---|---|---|
| Thousands | 1,000 | M |
| Hundreds | 900 | CM |
| Tens | 90 | XC |
| Ones | 4 | IV |
Result: MCMXCIV
Example: 2,026
| Place | Value | Roman |
|---|---|---|
| Thousands | 2,000 | MM |
| Tens | 20 | XX |
| Ones | 6 | VI |
Result: MMXXVI
Quick Reference: All Place Values
| Ones | Tens | Hundreds | Thousands |
|---|---|---|---|
| 1 = I | 10 = X | 100 = C | 1,000 = M |
| 2 = II | 20 = XX | 200 = CC | 2,000 = MM |
| 3 = III | 30 = XXX | 300 = CCC | 3,000 = MMM |
| 4 = IV | 40 = XL | 400 = CD | |
| 5 = V | 50 = L | 500 = D | |
| 6 = VI | 60 = LX | 600 = DC | |
| 7 = VII | 70 = LXX | 700 = DCC | |
| 8 = VIII | 80 = LXXX | 800 = DCCC | |
| 9 = IX | 90 = XC | 900 = CM |
Converting Roman Numerals to Numbers
Read left to right. If a symbol is smaller than the one after it, subtract. Otherwise, add.
Example: MCMXLIV
- M = 1,000 (add)
- CM = 900 (C before M, subtract)
- XL = 40 (X before L, subtract)
- IV = 4 (I before V, subtract)
- Total: 1,944
Chart: 1 to 100
| 1 = I | 11 = XI | 21 = XXI | 31 = XXXI | 41 = XLI |
| 2 = II | 12 = XII | 22 = XXII | 32 = XXXII | 42 = XLII |
| 3 = III | 13 = XIII | 23 = XXIII | 33 = XXXIII | 43 = XLIII |
| 4 = IV | 14 = XIV | 24 = XXIV | 34 = XXXIV | 44 = XLIV |
| 5 = V | 15 = XV | 25 = XXV | 35 = XXXV | 45 = XLV |
| 6 = VI | 16 = XVI | 26 = XXVI | 36 = XXXVI | 46 = XLVI |
| 7 = VII | 17 = XVII | 27 = XXVII | 37 = XXXVII | 47 = XLVII |
| 8 = VIII | 18 = XVIII | 28 = XXVIII | 38 = XXXVIII | 48 = XLVIII |
| 9 = IX | 19 = XIX | 29 = XXIX | 39 = XXXIX | 49 = XLIX |
| 10 = X | 20 = XX | 30 = XXX | 40 = XL | 50 = L |
| 51 = LI | 61 = LXI | 71 = LXXI | 81 = LXXXI | 91 = XCI |
| 52 = LII | 62 = LXII | 72 = LXXII | 82 = LXXXII | 92 = XCII |
| 53 = LIII | 63 = LXIII | 73 = LXXIII | 83 = LXXXIII | 93 = XCIII |
| 54 = LIV | 64 = LXIV | 74 = LXXIV | 84 = LXXXIV | 94 = XCIV |
| 55 = LV | 65 = LXV | 75 = LXXV | 85 = LXXXV | 95 = XCV |
| 56 = LVI | 66 = LXVI | 76 = LXXVI | 86 = LXXXVI | 96 = XCVI |
| 57 = LVII | 67 = LXVII | 77 = LXXVII | 87 = LXXXVII | 97 = XCVII |
| 58 = LVIII | 68 = LXVIII | 78 = LXXVIII | 88 = LXXXVIII | 98 = XCVIII |
| 59 = LIX | 69 = LXIX | 79 = LXXIX | 89 = LXXXIX | 99 = XCIX |
| 60 = LX | 70 = LXX | 80 = LXXX | 90 = XC | 100 = C |
Key Milestone Numbers
| Number | Roman | Why It Matters |
|---|---|---|
| 4 | IV | First use of the subtraction rule |
| 9 | IX | Subtractive pair with X |
| 49 | XLIX | Not IL — a common mistake |
| 99 | XCIX | Not IC — another common mistake |
| 400 | CD | C subtracted from D |
| 999 | CMXCIX | Not IM — all three subtractive tiers |
| 1,666 | MDCLXVI | Uses every symbol exactly once, in order |
| 3,888 | MMMDCCCLXXXVIII | Longest Roman numeral under 4,000 (15 chars) |
| 3,999 | MMMCMXCIX | Highest standard Roman numeral |
Numbers Above 3,999
Standard Roman numerals max out at 3,999 (MMMCMXCIX). For larger numbers, the Romans used the vinculum: a line above a numeral that multiplies its value by 1,000.
| Symbol | Value |
|---|---|
| V | 5,000 |
| X | 10,000 |
| L | 50,000 |
| C | 100,000 |
| M | 1,000,000 |
A double overline multiplies by 1,000,000. In practice, numbers this large were rarely written in Roman times — they used words instead.
Common Mistakes
- IL for 49 — wrong. Only I before V and X is valid. Correct: XLIX.
- IC for 99 — wrong. Correct: XCIX.
- IIII for 4 — technically non-standard, but accepted on clock faces.
- VV for 10 — never. V is not repeated. Use X.
- Mixing cases — Roman numerals are always uppercase. "xvii" is informal at best.
Where You'll See Them Today
- Clock faces — the most common everyday encounter
- Super Bowl — every year since V (1971), except 50
- Movie credits — copyright years at the end of films
- Sequels — Rocky II, Star Wars IV, Final Fantasy XVI
- Monarchs & popes — Elizabeth II, Benedict XVI
- Building cornerstones — construction years carved in stone
- Tattoos — dates and significant numbers
- Outlines — I, II, III as section markers
- Chemistry — oxidation states (FeIII)
Learn More About Roman Numerals
Why Are Roman Numerals Still Popular in the 21st Century?
From clock faces to tattoos to Super Bowl logos: why a 2,000-year-old number system refuses to die in the age of smartphones.
The Case for Roman Numerals in the 21st Century
Roman numerals are terrible for math. But for hierarchy, permanence, and visual distinction, they might be the best tool we have.
The History of Roman Numerals: They Are Not Actually Roman
From Etruscan tally marks to empire-wide accounting to decorative art. How seven impractical letters outlived the civilization that made them famous.
Super Bowl & Roman Numerals: Gladiators, Marketing, and the Letter L
Why the NFL numbers its biggest game like a Roman gladiator match. The one year they stopped, and what Super Bowl XIII tells us about superstition.