The calculated distance (air line) between Montignoso and Santo Stefano di Magra is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Santo Stefano di Magra is certainly longer, as only the direct route (as the crow flies) between Montignoso and Santo Stefano di Magra has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles