Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 11:55 and arrives at Koh Samui Samui International Airport at 13:05.
The flighttime is about 1h 10m. The distance travelled ("as the bird flies"): 113 Km. So the average speed is roughly 97 Km.
The best day to arrive at Bangkok is Thursday and it would be best to avoid Sunday, as prices are on average 126.23% higher than on Thursday. (Average prices, based on 5057615 datapoints.)
We have a lot more statistics for flights PG 135 and between Bangkok and Koh Samui.