The calculated distance (air line) between San Pietro in Casale and Castel Maggiore is approximately 9 miles respectively 14 kilometers.
By car or train, the actual journey to Castel Maggiore is certainly longer, as only the direct route (as the crow flies) between San Pietro in Casale and Castel Maggiore has been calculated here.
Air line (approximately)
14 kilometers
8 nautical miles