The calculated distance (air line) between Buchen in Odenwald and Karlsruhe is approximately 55 miles respectively 88 kilometers.
By car or train, the actual journey to Karlsruhe is certainly longer, as only the direct route (as the crow flies) between Buchen in Odenwald and Karlsruhe has been calculated here.
Air line (approximately)
88 kilometers
47 nautical miles