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 November and the most expensive month to fly is May. (Average prices, based on 3399 datapoints.)
The best day to arrive at Seoul is Wednesday and it would be best to avoid Friday, as prices are on average 22.1% higher than on Wednesday. (Average prices, based on 2610 datapoints.)
The cheapest airline flying to Seoul is Cebu Pacific Air. They are 40% cheaper than China Southern Airlines. (Average prices, based on 3511 datapoints.)
At Seoul the most flights depart around 23:00. (Hourly flights, based on 3638 datapoints.)
From Seoul it is on average the cheapest to fly to Shanghai and to Hong Kong. (Average prices, based on 2821 datapoints.)
From Seoul most of the flights depart to Tokyo, second best connected from Seoul is Singapore. (Daily flights, based on 97 datapoints.)