40 = XL
40 in Roman numerals is XL.
Forty written with the letters X L.
40 in words: Forty
Forty in Roman numerals is XL. It is short enough to write from memory once you know the pattern, and it turns up constantly on watch dials, book chapters and film sequels.
Everything in XL 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 40 breaks down
Reading XL from left to right, each group is added together to reach 40:
| Group | Value | Place |
|---|---|---|
| XL | 40 | tens |
| XL | 40 | total |
Frequently asked questions
What is 40 in Roman numerals?
40 in Roman numerals is XL.
How do you write 40 in words?
40 is written "Forty" in English.
What number comes before XL?
The number before XL is 39, written XXXIX in Roman numerals.
What number comes after XL?
The number after XL is 41, written XLI in Roman numerals.
Related numbers
Last updated July 22, 2026. Reviewed for accuracy against the standard rules for Roman numerals.