The calculated distance (air line) between Néa Michanióna and Petroúpolis is approximately 173 miles respectively 278 kilometers.
By car or train, the actual journey to Petroúpolis is certainly longer, as only the direct route (as the crow flies) between Néa Michanióna and Petroúpolis has been calculated here.
Air line (approximately)
278 kilometers
150 nautical miles