Flight Don Mueang International Airport departs from Bangkok Don Mueang International Airport at 20:00 and arrives at Guangzhou Guangzhou Baiyun International Airport at 23:45.
The flighttime is about 2h 45m. The distance travelled ("as the bird flies"): 1440 Km. So the average speed is roughly 524 Km.
There is an 1 hour time difference between Bangkok and Guangzhou