Please be aware that Seoul and Shanghai has multiple airports and that these results are for all airports serving the city.
The best month to fly between Seoul and Shanghai is May and the most expensive month to fly is June. (Average prices, based on 204 datapoints.)
The best day to arrive at Seoul is Thursday and it would be best to avoid Sunday, as prices are on average 48.36% higher than on Thursday. (Average prices, based on 408 datapoints.)
The cheapest airline flying from Seoul to Shanghai is China Southern Airlines. They are 33% cheaper than Korean Air. (Average prices, based on 217 datapoints.)
The best time to fly is at around 21. (Average prices, based on 337 datapoints.)