AirHint found the following cheapest return flights from Philadelphia (PHL) to Madrid (MAD) in September 2025 (see full year).

Return flights

21 Sep - 30 Sep	Delta
29 Sep - 03 Oct	jetBlue
28 Sep - 03 Oct	jetBlue
26 Sep - 18 Oct	Lufthansa
26 Sep - 29 Sep	Frontier Airlines
19 Sep - 17 Oct	Aer Lingus
26 Sep - 28 Sep	Spirit Airlines
17 Sep - 23 Sep	United
18 Sep - 22 Sep	Frontier Airlines
19 Sep - 24 Sep	American Airlines
21 Sep - 30 Sep	British Airways	direct
17 Sep - 11 Oct	British Airways
19 Sep - 24 Sep	American Airlines	direct
19 Sep - 17 Oct	American Airlines	direct
26 Sep - 28 Sep	British Airways	direct
17 Sep - 23 Sep	Iberia	direct
28 Sep - 03 Oct	Finnair	direct
29 Sep - 03 Oct	American Airlines	direct

Also check the deals for one-way flights from Philadelphia to Madrid in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Philadelphia to Madrid in September from $657

Return flights