Spirit's charges for all carry-on and checked baggage. The "Bare Fare" allows customers to bring one personal item on board for free, which must be small enough to be stowed away underneath a seat, such as a backpack or purse.
According to Spirit's website, the fee for a single checked bag ranges from $21 to $100, as of 2015. Prices are determined based on when the customer purchases the baggage fee. If a checked bag is added during online booking, the customer receives the lowest fee. If a checked bag is added during online check-in or at the airport, the fees are higher. Fees also increase depending on the number of checked bags. Additional fees of $25 to $150 are assessed for overweight or oversized baggage.