The calculated distance (air line) between Thalwil / Dorfkern and Luzern is approximately 21 miles respectively 33 kilometers.
By car or train, the actual journey to Luzern is certainly longer, as only the direct route (as the crow flies) between Thalwil / Dorfkern and Luzern has been calculated here.
Air line (approximately)
33 kilometers
18 nautical miles