The calculated distance (air line) between Katlenburg-Lindau and Hamburg-Mitte is approximately 129 miles respectively 208 kilometers.
By car or train, the actual journey to Hamburg-Mitte is certainly longer, as only the direct route (as the crow flies) between Katlenburg-Lindau and Hamburg-Mitte has been calculated here.
Air line (approximately)
208 kilometers
112 nautical miles