Are there nonstop flights from Dehradun (DED) to Bangkok (BKK)?

No. The fastest connection is via Kolkata, about 4h 29m of total flying time.

What is the fastest connection from Dehradun (DED) to Bangkok (BKK)?

via Kolkata ≈ 4h 29m, via New Delhi ≈ 4h 43m, via Hyderabad ≈ 5h 33m (estimated flying time, excluding layovers).

from 15,000 ANA miles (economy, one way, based on the published award charts).

Dehradun Jolly Grant Airport (DED) to Suvarnabhumi Airport (BKK)・2,954 km

No nonstop flights. The fastest connection is via Kolkata (CCU), about 4h 29m of flying time (layover not included).

With milesANA 15,000 miles+ (via DEL)Economy, one way, estimate. Tap a connection for miles by cabin.

None.

8 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.