Please be aware that Seoul and Bangkok has multiple airports and that these results are for all airports serving the city.
The best month to fly between Seoul and Bangkok is June and the most expensive month to fly is May. (Average prices, based on 216 datapoints.)
The best day to arrive at Seoul is Monday and it would be best to avoid Thursday, as prices are on average 98.82% higher than on Monday. (Average prices, based on 219 datapoints.)
The cheapest airline flying from Seoul to Bangkok is Jeju Air. They are 67% cheaper than Korean Air. (Average prices, based on 229 datapoints.)