Are there nonstop flights from Singapore (SIN) to Bangkok (DMK)?

Yes. Thai AirAsia, Thai Lion Air fly this route. Flight time is about 2h 12m.

What is the fastest connection from Singapore (SIN) to Bangkok (DMK)?

via Na Thon ≈ 2h 46m, via Hat Yai ≈ 2h 47m, via Phu Quoc Island ≈ 2h 48m (estimated flying time, excluding layovers).

from 12,000 JAL miles (economy, one way, based on the published award charts).

Singapore Changi Airport (SIN) to Don Mueang International Airport (DMK)・1,446 km

Nonstop flights available (2 airlines). Flight time about 2h 12m. Nonstop return flights also operate.

With milesJAL 12,000 miles+ (via USM)Economy, one way, estimate. Tap a connection for miles by cabin.

20 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.