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

Return flights

31 Aug - 11 Sep	Iberia
31 Aug - 08 Sep	Air Canada
31 Aug - 07 Sep	Lufthansa
30 Aug - 20 Sep	Icelandair
30 Aug - 12 Sep	Icelandair
30 Aug - 11 Sep	Icelandair
31 Aug - 05 Sep	Aer Lingus
31 Aug - 20 Sep	Air Canada
30 Aug - 14 Sep	Icelandair
30 Aug - 05 Sep	Icelandair

Also check the deals for one-way flights from Washington 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 Washington to London in August from $775

Return flights