Denver (DEN) to Philadelphia (PHL): 1,554 miles (2,501 km) great-circle, about 3h 35m nonstop by our estimate. Cheapest fare observed: $150 round-trip on Frontier, with 1 stop, departing May 14, 2026.
$150 round-trip, Frontier F92440, departing 2026-05-14 at 07:00, returning 2026-05-16. The recorded itinerary left on a Thursday, returning on a Saturday 2 nights later; the fare was observed 19 days before departure. "Book this flight" opens Kiwi.com with the same airline and dates.
At $150, it ranked 6th of the 30 round-trip fares we recorded from DEN (median $204). That is 9.7 cents per great-circle mile (round-trip price over one-way distance), below the DEN median of 16.1 cents across 30 round-trip routes.
Routes from DEN of similar length: Orlando (1,539 mi) at $193 and Tampa (1,505 mi) at $183.
Frontier had the cheapest fare on 19 of 30 DEN routes. It is the 11th longest of the 30 routes we track from DEN.
Of 13 departure airports with a fare to Philadelphia, Denver (DEN) ranked 7th at $150. Lowest: $69 from Tampa (TPA); highest: $413 from Punta Cana (PUJ); 5 nonstop. Cheapest-fare airlines (routes): Frontier (10), Southwest (1), Spirit (1) and Sun Country (1).
The reverse, Philadelphia (PHL) to Denver (DEN), was $216 round-trip on Frontier, 1 stop, departing July 10, 2026. Philadelphia to Denver flights.
Travelpayouts fares (cheapest per route, observed April 25, 2026); OurAirports coordinates and elevations; IANA zones America/Denver, America/New_York; flight time is our estimate.