The calculated distance (air line) between Farnham Royal and Southend-on-Sea is approximately 57 miles respectively 92 kilometers.
By car or train, the actual journey to Southend-on-Sea is certainly longer, as only the direct route (as the crow flies) between Farnham Royal and Southend-on-Sea has been calculated here.
Air line (approximately)
92 kilometers
50 nautical miles