The calculated distance (air line) between Thalwil / Dorfkern and Rapperswil is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Rapperswil is certainly longer, as only the direct route (as the crow flies) between Thalwil / Dorfkern and Rapperswil has been calculated here.
Air line (approximately)
21 kilometers
11 nautical miles