This is live pricing from Travelpayouts' aggregation of 40+ booking engines. The $358 fare is the cheapest current round-trip from Philadelphia (PHL) to STL on Frontier flight F92513, departing 2026-07-23 at 12:44 with return on 2026-07-26.

Clicking "Book this flight" opens Kiwi.com with this exact flight pre-filtered — same airline, same dates, same passenger count.