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

Return flights

11 Aug - 20 Aug	Spirit Airlines
11 Aug - 26 Aug	Spirit Airlines
09 Aug - 25 Aug	Frontier Airlines
11 Aug - 19 Aug	Spirit Airlines
01 Aug - 15 Sep	Spirit Airlines
18 Aug - 15 Sep	Spirit Airlines
09 Aug - 24 Aug	Spirit Airlines
16 Aug - 23 Aug	Spirit Airlines
08 Aug - 23 Aug	Spirit Airlines
12 Aug - 16 Sep	jetBlue
13 Aug - 18 Aug	Spirit Airlines
01 Aug - 31 Aug	Spirit Airlines
17 Aug - 23 Aug	Spirit Airlines
28 Aug - 02 Sep	Frontier Airlines
22 Aug - 01 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 421€

Return flights