Are there nonstop flights from Riyadh (RUH) to Kathmandu (KTM)?

Yes. Nepal Airlines, Himalaya Airlines fly this route. Flight time is about 5h 2m.

What is the fastest connection from Riyadh (RUH) to Kathmandu (KTM)?

via New Delhi ≈ 5h 32m, via Doha ≈ 5h 32m, via Sharjah ≈ 5h 33m (estimated flying time, excluding layovers).

from 23,000 JAL miles, from 36,000 ANA miles (economy, one way, based on the published award charts).

King Khalid International Airport (RUH) to Tribhuvan International Airport (KTM)・3,849 km

Nonstop flights available (2 airlines). Flight time about 5h 2m. Nonstop return flights also operate.

With milesJAL 23,000 miles+ (via DOH)ANA 36,000 miles+ (via DEL)Economy, one way, estimate. Tap a connection for miles by cabin.

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.