AirHint found the following cheapest return flights from Philadelphia (PHL) to London (LGW) in August 2025 (see full year).

Return flights

13 Aug - 20 Aug	Spirit Airlines
19 Aug - 26 Aug	Spirit Airlines
19 Aug - 24 Aug	Spirit Airlines
18 Aug - 26 Aug	Spirit Airlines
22 Aug - 26 Aug	Spirit Airlines
11 Aug - 19 Aug	Frontier Airlines
21 Aug - 26 Aug	Spirit Airlines
22 Aug - 25 Aug	Spirit Airlines
23 Aug - 31 Aug	Delta
11 Aug - 18 Aug	Spirit Airlines
30 Aug - 07 Sep	Frontier Airlines
28 Aug - 09 Sep	Frontier Airlines
29 Aug - 03 Sep	Spirit Airlines
29 Aug - 05 Sep	Aer Lingus
29 Aug - 07 Sep	Spirit Airlines
29 Aug - 06 Sep	Spirit Airlines

Also check the deals for one-way flights from Philadelphia to London in August.

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 London in August from 444€

Return flights