Air distance from Hanoi, Vietnam to Ulaanbaatar, Mongolia is 1834.6 Miles (2952.5 Kilometers / 1593.1 Nautical Miles).
3 hrs, 48 mins is the flight duration between Hanoi and Ulaanbaatar. This is the In-The-Air flight time. You should also add the taxi time, airport wait times and possible delays due to bad weather, etc. for the total flight duration time.