All checked luggage on Sun Country Airlines are subject to fees. Checked baggage cannot weigh more than 50 pounds and 62 linear inches, per their baggage allowance. If you choose the bag option when making your reservation or when checking in online, your first and second checked bags will cost you each; if you want to check a bag at the airport, it will cost you. The cost of a third checked bag is, whether you pay in advance or at the airport.
