AirHint found the following cheapest return flights from Seattle (SEA) to Copenhagen (CPH) in August 2025 (see full year).

Return flights

17 Aug - 24 Aug	Icelandair
08 Aug - 18 Aug	Icelandair
14 Aug - 23 Aug	Icelandair
20 Aug - 25 Aug	Icelandair
07 Aug - 20 Aug	Icelandair
21 Aug - 28 Aug	Icelandair
26 Aug - 05 Sep	Icelandair
27 Aug - 06 Sep	Icelandair
22 Aug - 27 Aug	Icelandair
21 Aug - 26 Aug	KLM
24 Aug - 08 Sep	Icelandair
24 Aug - 08 Sep	Scandinavian Airlines	direct
28 Aug - 04 Sep	Icelandair
30 Aug - 06 Sep	Icelandair
19 Aug - 26 Aug	Icelandair
23 Aug - 30 Aug	Icelandair
25 Aug - 01 Sep	Icelandair
27 Aug - 06 Sep	Scandinavian Airlines	direct

Also check the deals for one-way flights from Seattle to Copenhagen 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 Seattle to Copenhagen in August from 394€

Return flights