The calculated distance (air line) between Frenštát pod Radhoštěm and Brno is approximately 76 miles respectively 123 kilometers.
By car or train, the actual journey to Brno is certainly longer, as only the direct route (as the crow flies) between Frenštát pod Radhoštěm and Brno has been calculated here.
Air line (approximately)
123 kilometers
66 nautical miles