The calculated distance (air line) between Neustadt am Rübenberge and Marienthal is approximately 78 miles respectively 125 kilometers.
By car or train, the actual journey to Marienthal is certainly longer, as only the direct route (as the crow flies) between Neustadt am Rübenberge and Marienthal has been calculated here.
Air line (approximately)
125 kilometers
68 nautical miles