The calculated distance (air line) between Frenštát pod Radhoštěm and Ostrava is approximately 20 miles respectively 32 kilometers.
By car or train, the actual journey to Ostrava is certainly longer, as only the direct route (as the crow flies) between Frenštát pod Radhoštěm and Ostrava has been calculated here.
Air line (approximately)
32 kilometers
17 nautical miles