The calculated distance (air line) between Bu'ayna-Nujaydat and Kfar Saba is approximately 51 miles respectively 83 kilometers.
By car or train, the actual journey to Kfar Saba is certainly longer, as only the direct route (as the crow flies) between Bu'ayna-Nujaydat and Kfar Saba has been calculated here.
Air line (approximately)
83 kilometers
45 nautical miles