The best month to fly between Koh Samui and Bangkok is October and the most expensive month to fly is September. (Average prices, based on 365 datapoints.)
The best day to arrive at Koh Samui is Monday and it would be best to avoid Thursday, as prices are on average 19.89% higher than on Monday. (Average prices, based on 536 datapoints.)
The best time to fly is at around 16. (Average prices, based on 612 datapoints.)