The calculated distance (air line) between Saint-Hilaire-de-Riez and Le Mans is approximately 134 miles respectively 216 kilometers.
By car or train, the actual journey to Le Mans is certainly longer, as only the direct route (as the crow flies) between Saint-Hilaire-de-Riez and Le Mans has been calculated here.
Air line (approximately)
216 kilometers
116 nautical miles