The calculated distance (air line) between Six-Fours-les-Plages and Grenoble is approximately 144 miles respectively 232 kilometers.
By car or train, the actual journey to Grenoble is certainly longer, as only the direct route (as the crow flies) between Six-Fours-les-Plages and Grenoble has been calculated here.
Air line (approximately)
232 kilometers
125 nautical miles