Please be aware that Seoul has multiple airports and that these results are for all airports serving the city.
The best month to arrive at Seoul is November and the most expensive month to fly is October. (Average prices, based on 4300 datapoints.)
The best day to arrive at Seoul is Wednesday and it would be best to avoid Saturday, as prices are on average 22.45% higher than on Wednesday. (Average prices, based on 4440 datapoints.)
The cheapest airline flying to Seoul is Cebu Pacific Air. They are 33% cheaper than Shanghai Airlines. (Average prices, based on 4404 datapoints.)
At Seoul the most flights depart around 23:00. (Hourly flights, based on 4565 datapoints.)
From Seoul it is on average the cheapest to fly to Manila and to Osaka. (Average prices, based on 267 datapoints.)
From Seoul most of the flights depart to Tokyo, second best connected from Seoul is Singapore. (Daily flights, based on 96 datapoints.)