The calculated distance (air line) between Hoo and Purfleet-on-Thames is approximately 14 miles respectively 23 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 Hoo and Purfleet-on-Thames has been calculated here.
Air line (approximately)
23 kilometers
13 nautical miles