Number
18 in Roman numerals
18 is written XVIII
Type any other number or numeral below to convert it.
Above 3,999? Type the barred part in brackets, e.g. (IV)CC = 4,200.
How XVIII is built
Roman numerals are written one decimal place at a time, largest first.
- Xtens · 1X is 10.
- VIIIones · 8V (5) plus III (3) makes 8.
10 + 8 = 18
No subtraction is needed here: every letter is the same size or smaller than the one before it, so you simply add them up.
About the number 18
- 18 is even and can be split into prime factors: 2 × 3 × 3, or in Roman numerals II × III × III.
- XVIII has 5 letters. 604 of the numbers up to 1,000 have longer numerals.
- As a day of the month, XVIII is the 18th. Write a date
Counting from 11 to 20
| Number | Roman numeral |
|---|---|
| 11 | XI |
| 12 | XII |
| 13 | XIII |
| 14 | XIV |
| 15 | XV |
| 16 | XVI |
| 17 | XVII |
| 18 | XVIII |
| 19 | XIX |
| 20 | XX |