Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 12:05 and arrives at Rome Leonardo da Vinci–Fiumicino Airport at 19:20.
The flighttime is about 13h 15m. The distance travelled ("as the bird flies"): 9703 Km. So the average speed is roughly 732 Km.
There is an 6 hour time difference between Bangkok and Rome