The calculated distance (air line) between Uster / Kirch-Uster and Rapperswil is approximately 10 miles respectively 16 kilometers.
By car or train, the actual journey to Rapperswil is certainly longer, as only the direct route (as the crow flies) between Uster / Kirch-Uster and Rapperswil has been calculated here.
Air line (approximately)
16 kilometers
8 nautical miles