The calculated distance (air line) between Mazār-e Sharīf and Khulm is approximately 33 miles respectively 52 kilometers.
By car or train, the actual journey to Khulm is certainly longer, as only the direct route (as the crow flies) between Mazār-e Sharīf and Khulm has been calculated here.
Air line (approximately)
52 kilometers
28 nautical miles