The calculated distance (air line) between Starý Bohumín and Mladá Boleslav is approximately 156 miles respectively 251 kilometers.
By car or train, the actual journey to Mladá Boleslav is certainly longer, as only the direct route (as the crow flies) between Starý Bohumín and Mladá Boleslav has been calculated here.
Air line (approximately)
251 kilometers
135 nautical miles