AirHint found the following cheapest return flights from London (LHR) to Boston (BOS) in August 2025 (see full year).

Return flights

29 Aug - 13 Sep	SWISS
27 Aug - 12 Sep	Air Canada
27 Aug - 20 Sep	Air Canada
30 Aug - 13 Sep	Lufthansa
29 Aug - 11 Sep	SWISS
29 Aug - 29 Sep	SWISS
29 Aug - 12 Sep	SWISS
07 Aug - 11 Aug	Austrian Airlines
29 Aug - 01 Sep	Scandinavian Airlines
31 Aug - 10 Sep	Air Canada
28 Aug - 14 Sep	Air Canada
20 Aug - 27 Aug	Finnair
18 Aug - 25 Aug	Finnair
05 Aug - 12 Aug	Virgin Atlantic	direct
18 Aug - 26 Aug	Virgin Atlantic	direct
18 Aug - 26 Aug	Finnair
06 Aug - 12 Aug	Finnair
18 Aug - 25 Aug	Virgin Atlantic	direct
05 Aug - 11 Aug	Virgin Atlantic	direct
19 Aug - 27 Aug	Finnair

Also check the deals for one-way flights from London to Boston 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 London to Boston in August from 371€

Return flights