The calculated distance (air line) between Bīr el Maksūr and Ashkelon is approximately 85 miles respectively 138 kilometers.
By car or train, the actual journey to Ashkelon is certainly longer, as only the direct route (as the crow flies) between Bīr el Maksūr and Ashkelon has been calculated here.
Air line (approximately)
138 kilometers
74 nautical miles