AirHint found the following cheapest return flights from Boston (BOS) to Frankfurt (FRA) in September 2025 (see full year).

Return flights

18 Sep - 22 Sep	Icelandair
24 Sep - 01 Oct	Icelandair
11 Sep - 26 Sep	Icelandair
02 Sep - 21 Sep	Icelandair
15 Sep - 27 Sep	Icelandair
02 Sep - 27 Sep	Icelandair
01 Sep - 27 Sep	Icelandair
16 Sep - 20 Sep	Icelandair
06 Sep - 11 Sep	Condor	direct
29 Sep - 06 Oct	Icelandair
16 Sep - 01 Oct	Icelandair
09 Sep - 16 Sep	Icelandair
11 Sep - 18 Sep	Icelandair
17 Sep - 01 Oct	Delta
18 Sep - 16 Oct	Condor	direct
13 Sep - 04 Oct	Aer Lingus
26 Sep - 05 Oct	Aer Lingus
26 Sep - 03 Oct	Delta
21 Sep - 11 Oct	Aer Lingus
12 Sep - 04 Oct	KLM

Also check the deals for one-way flights from Boston to Frankfurt 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 Boston to Frankfurt in September from $464

Return flights