40 in Roman numerals

40 = XL

Working: XL = 40

The number 40 is written as XL in Roman numerals.

Roman numerals are built by adding symbol values together from largest to smallest: XL = 40. Where a smaller symbol appears before a larger one — as in IV for 4 or IX for 9 — it is subtracted rather than added, which keeps the notation short.

Structurally, XL is 2 symbols long. It uses the subtractive pair and XL, which must be read as a unit rather than symbol by symbol. No symbol repeats.

XL is ten subtracted from fifty. It is the third of the six subtractive pairs the system uses — IV, IX, XL, XC, CD and CM — each of which places a smaller symbol before the next available larger one to avoid a four-symbol run.

Nearby numbers

Number	Roman numeral
16	XVI
18	XVIII
19	XIX
20	XX
25	XXV
30	XXX
50	L
60	LX

Try another value

Decimal number (1–3999)

Roman numeral

MMXXIV

Reference

X10

L50

C100

D500

M1000

Frequently asked questions

How do you write 40 in Roman numerals?

40 is written XL. It breaks down as XL = 40.

What are the seven Roman numeral symbols?

I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1,000. All Roman numerals are combinations of these seven symbols, and there is no symbol for zero.

For any other value, use the full Roman Numeral Converter on BrainVert.