Air distance from Chicago, USA to Ulaanbaatar, Mongolia is 6224.6 Miles (10017.6 Kilometers / 5405.5 Nautical Miles).
Flight duration time from Chicago to Ulaanbaatar is 12 hrs, 55 mins. 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.