The calculated distance (air line) between Bourg-en-Bresse and Grenoble is approximately 75 miles respectively 120 kilometers.
By car or train, the actual journey to Grenoble is certainly longer, as only the direct route (as the crow flies) between Bourg-en-Bresse and Grenoble has been calculated here.
Air line (approximately)
120 kilometers
65 nautical miles