The calculated distance (air line) between Hŭngnam and P’yŏngsŏng is approximately 102 miles respectively 165 kilometers.
By car or train, the actual journey to P’yŏngsŏng is certainly longer, as only the direct route (as the crow flies) between Hŭngnam and P’yŏngsŏng has been calculated here.
Air line (approximately)
165 kilometers
89 nautical miles