The calculated distance (air line) between Castelnovo ne'Monti and Pontremoli is approximately 26 miles respectively 42 kilometers.
By car or train, the actual journey to Pontremoli is certainly longer, as only the direct route (as the crow flies) between Castelnovo ne'Monti and Pontremoli has been calculated here.
Air line (approximately)
42 kilometers
23 nautical miles