The calculated distance (air line) between Saint-Macaire-en-Mauges and Le Havre is approximately 171 miles respectively 276 kilometers.
By car or train, the actual journey to Le Havre is certainly longer, as only the direct route (as the crow flies) between Saint-Macaire-en-Mauges and Le Havre has been calculated here.
Air line (approximately)
276 kilometers
149 nautical miles