The calculated distance (air line) between San Martino in Rio and Castelnovo di Sotto is approximately 12 miles respectively 19 kilometers.
By car or train, the actual journey to Castelnovo di Sotto is certainly longer, as only the direct route (as the crow flies) between San Martino in Rio and Castelnovo di Sotto has been calculated here.
Air line (approximately)
19 kilometers
10 nautical miles