The calculated distance (air line) between Zürich (Kreis 11) / Oerlikon and Rapperswil is approximately 18 miles respectively 29 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 11) / Oerlikon and Rapperswil has been calculated here.
Air line (approximately)
29 kilometers
16 nautical miles