The calculated distance (air line) between Salgótarján and Budapest XXI. kerület is approximately 57 miles respectively 92 kilometers.
By car or train, the actual journey to Budapest XXI. kerület is certainly longer, as only the direct route (as the crow flies) between Salgótarján and Budapest XXI. kerület has been calculated here.
Air line (approximately)
92 kilometers
50 nautical miles