Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 11:40 and arrives at Koh Samui Samui International Airport at 12:45.
The flighttime is about 1h 05m. The distance travelled ("as the bird flies"): 113 Km. So the average speed is roughly 104 Km.
The best day to arrive at Bangkok is Tuesday and it would be best to avoid Sunday, as prices are on average 177.13% higher than on Tuesday. (Average prices, based on 5446879 datapoints.)
We have a lot more statistics for flights PG 133 and between Bangkok and Koh Samui.
