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

Return flights

28 Oct - 04 Nov	Icelandair
08 Oct - 15 Oct	Icelandair
11 Oct - 18 Oct	Icelandair
14 Oct - 21 Oct	Icelandair
17 Oct - 24 Oct	Icelandair
20 Oct - 27 Oct	Icelandair
23 Oct - 30 Oct	Icelandair
18 Oct - 26 Oct	Icelandair
02 Oct - 09 Oct	Icelandair
05 Oct - 12 Oct	Icelandair
10 Oct - 23 Oct	Delta

Also check the deals for one-way flights from Seattle to Copenhagen in October.

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 October from 378€

Return flights