Please be aware that Bangkok has multiple airports and that these results are for all airports serving the city.
The best month to fly between Bangkok and Hong Kong is August and the most expensive month to fly is February. (Average prices, based on 359 datapoints.)
The best day to arrive at Bangkok is Tuesday and it would be best to avoid Wednesday, as prices are on average 53.86% higher than on Tuesday. (Average prices, based on 1638 datapoints.)
The cheapest airline flying from Bangkok to Hong Kong is Hong Kong Express. They are 62% cheaper than Cathay Pacific. (Average prices, based on 373 datapoints.)
The best time to fly is at around 2. (Average prices, based on 821 datapoints.)