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

Return flights

02 Sep - 09 Sep	TAP
14 Sep - 21 Sep	Icelandair
20 Sep - 24 Sep	Icelandair
06 Sep - 13 Sep	Icelandair
09 Sep - 16 Sep	Icelandair
12 Sep - 19 Sep	Icelandair
03 Sep - 10 Sep	Icelandair
30 Sep - 07 Oct	Icelandair
25 Sep - 02 Oct	Icelandair
20 Sep - 27 Sep	Icelandair
15 Sep - 22 Sep	Icelandair
02 Sep - 09 Sep	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 $419

Return flights