Spirit Airlines passengers must pay for carry-on and checked baggage. This is so that the airline can keep its ticket prices low. However, a personal item that fits entirely in the smaller box (such as a purse, small backpack, etc.) is included with your ticket. Anything larger, such as a standard carry-on or checked bag, will need to be paid for.
A personal item must not measure more than 45 x 35 x 20 cm.
The fee for bringing a larger item on board varies depending on when the allowance is actually purchased. If you purchase it online during the flight booking process, the fee is usually $37.