The calculated distance (air line) between Rishon LeTsiyyon and Kfar Saba is approximately 16 miles respectively 25 kilometers.
By car or train, the actual journey to Kfar Saba is certainly longer, as only the direct route (as the crow flies) between Rishon LeTsiyyon and Kfar Saba has been calculated here.
Air line (approximately)
25 kilometers
14 nautical miles