AirHint found the following cheapest return flights from Philadelphia (PHL) to Bangkok (BKK) in December 2025 (see full year).

Return flights

04 Dec - 12 Dec	Frontier Airlines
07 Dec - 13 Dec	Delta
27 Dec - 14 Jan	Frontier Airlines
14 Dec - 21 Dec	Alaska Airlines
25 Dec - 08 Jan	Frontier Airlines
29 Dec - 10 Jan	Frontier Airlines
12 Dec - 19 Dec	Frontier Airlines
30 Dec - 06 Jan	Qatar Airways
13 Dec - 30 Dec	Aer Lingus
16 Dec - 09 Jan	Hawaiian Airlines
26 Dec - 30 Dec	Frontier Airlines
18 Dec - 23 Dec	Frontier Airlines
27 Dec - 05 Jan	Frontier Airlines
18 Dec - 14 Jan	Spirit Airlines
20 Dec - 30 Dec	Air Canada

Also check the deals for one-way flights from Philadelphia to Bangkok in December.

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 Philadelphia to Bangkok in December from 939€

Return flights