The calculated distance (air line) between Sidi Bou Saïd and El Kef is approximately 103 miles respectively 165 kilometers.
By car or train, the actual journey to El Kef is certainly longer, as only the direct route (as the crow flies) between Sidi Bou Saïd and El Kef has been calculated here.
Air line (approximately)
165 kilometers
89 nautical miles