The calculated distance (air line) between Amstetten and Klagenfurt am Wörthersee is approximately 107 miles respectively 172 kilometers.
By car or train, the actual journey to Klagenfurt am Wörthersee is certainly longer, as only the direct route (as the crow flies) between Amstetten and Klagenfurt am Wörthersee has been calculated here.
Air line (approximately)
172 kilometers
93 nautical miles