Please be aware that Seoul has multiple airports and that these results are only for Incheon International Airport.
The best month to arrive at Seoul is January and the most expensive month to fly is September. (Average prices, based on 430 datapoints.)
The best day to arrive at Seoul is Wednesday and it would be best to avoid Saturday, as prices are on average 25.69% higher than on Wednesday. (Average prices, based on 2756 datapoints.)
The cheapest airline flying to Seoul is Philippines AirAsia. They are 21% cheaper than China Eastern Airlines. (Average prices, based on 614 datapoints.)
At Seoul the most flights depart around 09:00. (Hourly flights, based on 1043 datapoints.)
From Seoul it is on average the cheapest to fly to Shanghai and to Osaka. (Average prices, based on 450 datapoints.)
From Seoul most of the flights depart to Tokyo, second best connected from Seoul is Osaka. (Daily flights, based on 212 datapoints.)