Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 19:40 and arrives at Singapore Changi Airport at 22:55.
The flighttime is about 2h 15m. The distance travelled ("as the bird flies"): 462 Km. So the average speed is roughly 205 Km.
There is an 1 hour time difference between Bangkok and Singapore
The best day to arrive at Bangkok is Tuesday and it would be best to avoid Friday, as prices are on average 53.5% higher than on Tuesday. (Average prices, based on 9431807 datapoints.)
We have a lot more statistics for flights QF 401 and between Bangkok and Singapore.