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

Return flights

24 Sep - 29 Sep	Ryanair
24 Sep - 01 Oct	Ryanair
20 Sep - 07 Oct	Ryanair
24 Sep - 07 Oct	Ryanair
24 Sep - 02 Oct	Ryanair
24 Sep - 30 Sep	Ryanair
24 Sep - 25 Oct	Ryanair
24 Sep - 26 Sep	Ryanair
24 Sep - 27 Sep	Ryanair	direct
23 Sep - 09 Oct	Ryanair
24 Sep - 01 Oct	Ryanair	direct
23 Sep - 29 Sep	Ryanair
20 Sep - 24 Sep	Ryanair
20 Sep - 25 Sep	Ryanair
23 Sep - 26 Sep	Ryanair
20 Sep - 01 Oct	Ryanair
28 Sep - 01 Oct	Ryanair
23 Sep - 25 Sep	Ryanair
25 Sep - 29 Sep	Ryanair
30 Sep - 30 Oct	Ryanair

Also check the deals for one-way flights from Frankfurt to Porto 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 Frankfurt to Porto in September from $117

Return flights