The calculated distance (air line) between Dinard and Châtillon-sur-Seiche is approximately 45 miles respectively 73 kilometers.
By car or train, the actual journey to Châtillon-sur-Seiche is certainly longer, as only the direct route (as the crow flies) between Dinard and Châtillon-sur-Seiche has been calculated here.
Air line (approximately)
73 kilometers
39 nautical miles