The calculated distance (air line) between Saint-Macaire-en-Mauges and Rennes is approximately 75 miles respectively 121 kilometers.
By car or train, the actual journey to Rennes is certainly longer, as only the direct route (as the crow flies) between Saint-Macaire-en-Mauges and Rennes has been calculated here.
Air line (approximately)
121 kilometers
65 nautical miles