The calculated distance (air line) between Beaconsfield and Hemel Hempstead is approximately 13 miles respectively 21 kilometers.
By car or train, the actual journey to Hemel Hempstead is certainly longer, as only the direct route (as the crow flies) between Beaconsfield and Hemel Hempstead has been calculated here.
Air line (approximately)
21 kilometers
11 nautical miles