The calculated distance (air line) between Kapsan-ŭp and P’yŏngsŏng is approximately 180 miles respectively 290 kilometers.
By car or train, the actual journey to P’yŏngsŏng is certainly longer, as only the direct route (as the crow flies) between Kapsan-ŭp and P’yŏngsŏng has been calculated here.
Air line (approximately)
290 kilometers
157 nautical miles