Flight Suvarnabhumi Airport departs from Bangkok Suvarnabhumi Airport at 23:55 and arrives at Tokyo Narita International Airport at 08:00.
The flighttime is about 6h 05m. The distance travelled ("as the bird flies"): 4511 Km. So the average speed is roughly 742 Km.
There is an 2 hour time difference between Bangkok and Tokyo
The best day to arrive at Bangkok is Tuesday and it would be best to avoid Saturday, as prices are on average 81.85% higher than on Tuesday. (Average prices, based on 452227 datapoints.)
We have a lot more statistics for flights XJ 600 and between Bangkok and Tokyo.