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