The calculated distance (air line) between Le Mans and Montlouis-sur-Loire is approximately 52 miles respectively 83 kilometers.
By car or train, the actual journey to Montlouis-sur-Loire is certainly longer, as only the direct route (as the crow flies) between Le Mans and Montlouis-sur-Loire has been calculated here.
Air line (approximately)
83 kilometers
45 nautical miles