The calculated distance (air line) between Sankt Georgen im Schwarzwald and Nürnberg is approximately 155 miles respectively 249 kilometers.
By car or train, the actual journey to Nürnberg is certainly longer, as only the direct route (as the crow flies) between Sankt Georgen im Schwarzwald and Nürnberg has been calculated here.
Air line (approximately)
249 kilometers
134 nautical miles