Flight Don Mueang International Airport departs from Bangkok Don Mueang International Airport at 22:55 and arrives at Kolkata Netaji Subhas Chandra Bose International Airport at 23:59.
The flighttime is about 2h 34m. The distance travelled ("as the bird flies"): 1350 Km. So the average speed is roughly 526 Km.
There is an 1.5 hour time difference between Bangkok and Kolkata