The calculated distance (air line) between Napajedla and Mladá Boleslav is approximately 144 miles respectively 233 kilometers.
By car or train, the actual journey to Mladá Boleslav is certainly longer, as only the direct route (as the crow flies) between Napajedla and Mladá Boleslav has been calculated here.
Air line (approximately)
233 kilometers
125 nautical miles