The calculated distance (air line) between Sankt Pölten and Klagenfurt am Wörthersee is approximately 125 miles respectively 202 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 Sankt Pölten and Klagenfurt am Wörthersee has been calculated here.
Air line (approximately)
202 kilometers
109 nautical miles