The calculated distance (air line) between Nymburk and Mladá Boleslav is approximately 17 miles respectively 27 kilometers.
By car or train, the actual journey to Mladá Boleslav is certainly longer, as only the direct route (as the crow flies) between Nymburk and Mladá Boleslav has been calculated here.
Air line (approximately)
27 kilometers
15 nautical miles