Please be aware that Seoul and Jakarta has multiple airports and that these results are for all airports serving the city.
The best month to fly between Seoul and Jakarta is October and the most expensive month to fly is February. (Average prices, based on 1540 datapoints.)
The best day to arrive at Seoul is Thursday and it would be best to avoid Saturday, as prices are on average 24.94% higher than on Thursday. (Average prices, based on 1316 datapoints.)