Are there nonstop flights from Bangkok (DMK) to Ulaanbaatar (UBN)?

No. The fastest connection is via Beijing, about 6h 13m of total flying time.

What is the fastest connection from Bangkok (DMK) to Ulaanbaatar (UBN)?

via Beijing ≈ 6h 13m, via Guangzhou ≈ 6h 15m, via Tianjin ≈ 6h 19m (estimated flying time, excluding layovers).

Don Mueang International Airport (DMK) to Ulaanbaatar Chinggis Khaan International Airport (UBN)・3,795 km

No nonstop flights. The fastest connection is via Beijing (PKX), about 6h 13m of flying time (layover not included).

None.

15 one-stop options, sorted by estimated flying time. Tap one to see the airlines on each leg and booking links.

Times are estimated from distance. Check schedules, frequency and availability with the airline or a booking site.