The best month to fly between Koh Samui and Bangkok is August and the most expensive month to fly is July. (Average prices, based on 536 datapoints.)
The best day to arrive at Koh Samui is Friday and it would be best to avoid Wednesday, as prices are on average 28.34% higher than on Friday. (Average prices, based on 3017 datapoints.)
The best time to fly is at around 8. (Average prices, based on 674 datapoints.)