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 December. (Average prices, based on 4606 datapoints.)
The best day to arrive at Seoul is Wednesday and it would be best to avoid Saturday, as prices are on average 25.35% higher than on Wednesday. (Average prices, based on 2543 datapoints.)
The cheapest airline flying to Seoul is Air Seoul. They are 32% cheaper than China Eastern Airlines. (Average prices, based on 4830 datapoints.)
At Seoul the most flights depart around 23:00. (Hourly flights, based on 5317 datapoints.)
From Seoul it is on average the cheapest to fly to Shanghai and to Osaka. (Average prices, based on 549 datapoints.)
From Seoul most of the flights depart to Tokyo, second best connected from Seoul is Hong Kong. (Daily flights, based on 208 datapoints.)