The calculated distance (air line) between Zürich (Kreis 12) and Rapperswil is approximately 17 miles respectively 27 kilometers.
By car or train, the actual journey to Rapperswil is certainly longer, as only the direct route (as the crow flies) between Zürich (Kreis 12) and Rapperswil has been calculated here.
Air line (approximately)
27 kilometers
15 nautical miles