18 = XVIII
18 in Roman numerals is XVIII.
Eighteen written with the letters X V I I I.
18 in words: Eighteen
Eighteen in Roman numerals is XVIII. You build it as X (10) + VIII (8), writing the larger part first and reading left to right.
Everything in XVIII is additive here, so you simply add each letter's value together. Numbers like this are a good place to get comfortable before tackling the subtractive forms such as IV and IX.
How 18 breaks down
Reading XVIII from left to right, each group is added together to reach 18:
| Group | Value | Place |
|---|---|---|
| X | 10 | tens |
| VIII | 8 | ones |
| XVIII | 18 | total |
Frequently asked questions
What is 18 in Roman numerals?
18 in Roman numerals is XVIII.
How do you write 18 in words?
18 is written "Eighteen" in English.
What number comes before XVIII?
The number before XVIII is 17, written XVII in Roman numerals.
What number comes after XVIII?
The number after XVIII is 19, written XIX in Roman numerals.
Related numbers
Last updated July 22, 2026. Reviewed for accuracy against the standard rules for Roman numerals.