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