Carnival Cruise Lines
How Many Formal Nights?

There aren't many. Sometimes, none.

Carnival has a maximum of two formal nights even on its longest cruises.

On cruises with one formal night, the formal night is normally the second or third evening.

For cruises with two formal nights, the first formal night is the second or third evening.

The second formal night falls on the second or third evening prior to the end of the cruise.

Cruise length, number of formal nights

1-day cruise: no formal nights
2-5 day cruise: one formal night
6-17 day cruise: two formal nights

What to wear

Carnival's definition of formal attire is the following:

Tuxedo (optional)
Suit and tie
Sport coat, tie and slacks
Evening gown

Cocktail dress

Pantsuit