The calculated distance (air line) between Saint-Étienne-du-Rouvray and Le Mans is approximately 104 miles respectively 167 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-Étienne-du-Rouvray and Le Mans has been calculated here.
Air line (approximately)
167 kilometers
90 nautical miles