Frontier Airlines is an "Ultra-Low-Cost Carrier" (ULCC), meaning they allow very little for free to keep their base fares as low as possible. In 2026, the only item included in your base fare for free is one "Personal Item" (such as a small backpack or purse) that must fit entirely under the seat in front of you (max dimensions: 18 x 14 x 8 inches). Everything else comes with a fee, including overhead carry-on bags, checked luggage, and seat assignments. Even basic amenities like water, juice, or snacks on the plane must be purchased. However, Frontier does offer a unique "Kids Fly Free" program for members of their "Discount Den" subscription service on select dates. For 2026 travelers, the best way to get "extras" for free is to hold high-tier Frontier Miles Elite Status, which can grant you free carry-on bags, seat assignments, and priority boarding, effectively turning the budget experience into a full-service one for frequent "Discount Den" flyers.