The calculated distance (air line) between Khārk and As Saffānīyah is approximately 132 miles respectively 212 kilometers.
By car or train, the actual journey to As Saffānīyah is certainly longer, as only the direct route (as the crow flies) between Khārk and As Saffānīyah has been calculated here.
Air line (approximately)
212 kilometers
114 nautical miles