The calculated distance (air line) between Bexley and Purfleet-on-Thames is approximately 5 miles respectively 8 kilometers.
By car or train, the actual journey to Purfleet-on-Thames is certainly longer, as only the direct route (as the crow flies) between Bexley and Purfleet-on-Thames has been calculated here.
Air line (approximately)
8 kilometers
4 nautical miles