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

Return flights

23 Sep - 30 Sep	Condor	direct
18 Sep - 25 Sep	Condor	direct
18 Sep - 27 Sep	Air France
26 Sep - 05 Oct	Condor
18 Sep - 22 Sep	Condor	direct
18 Sep - 28 Sep	Condor	direct
18 Sep - 16 Oct	Condor	direct
28 Sep - 04 Oct	Condor
30 Sep - 25 Oct	Aer Lingus
18 Sep - 26 Sep	Condor
19 Sep - 23 Sep	Condor
25 Sep - 18 Oct	Azores Airlines
20 Sep - 04 Oct	Spirit Airlines
29 Sep - 03 Oct	Iberia
20 Sep - 27 Sep	Condor
18 Sep - 11 Oct	Lufthansa
19 Sep - 23 Sep	Lufthansa	direct
25 Sep - 18 Oct	Lufthansa	direct
16 Sep - 01 Oct	Lufthansa	direct
20 Sep - 27 Sep	Lufthansa	direct

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 443€

Return flights