The calculated distance (air line) between Hafendorf and Klagenfurt am Wörthersee is approximately 75 miles respectively 120 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 Hafendorf and Klagenfurt am Wörthersee has been calculated here.
Air line (approximately)
120 kilometers
65 nautical miles