The calculated distance (air line) between Bayt Ūmmar and Khān Yūnis is approximately 51 miles respectively 82 kilometers.
By car or train, the actual journey to Khān Yūnis is certainly longer, as only the direct route (as the crow flies) between Bayt Ūmmar and Khān Yūnis has been calculated here.
Air line (approximately)
82 kilometers
44 nautical miles