AirHint found the following cheapest return flights from Washington (IAD) to Copenhagen (CPH) in September 2025 (see full year).

Return flights

30 Sep - 07 Oct	Icelandair
05 Sep - 19 Sep	Icelandair
04 Sep - 11 Sep	Icelandair
06 Sep - 13 Sep	Icelandair
10 Sep - 17 Sep	Icelandair
12 Sep - 19 Sep	Icelandair
14 Sep - 19 Sep	Icelandair
12 Sep - 14 Sep	Icelandair
05 Sep - 27 Sep	Icelandair
29 Sep - 25 Oct	Icelandair
24 Sep - 01 Oct	Icelandair
27 Sep - 04 Oct	Icelandair
25 Sep - 02 Oct	Icelandair
23 Sep - 27 Sep	Icelandair
15 Sep - 19 Sep	Icelandair
28 Sep - 05 Oct	Icelandair
21 Sep - 11 Oct	Icelandair
24 Sep - 18 Oct	Icelandair
30 Sep - 07 Oct	Scandinavian Airlines	direct
29 Sep - 06 Oct	Scandinavian Airlines	direct

Also check the deals for one-way flights from Washington to Copenhagen in September.

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 Copenhagen in September from 401€

Return flights