The calculated distance (air line) between Chalfont St Giles and Hemel Hempstead is approximately 10 miles respectively 16 kilometers.
By car or train, the actual journey to Hemel Hempstead is certainly longer, as only the direct route (as the crow flies) between Chalfont St Giles and Hemel Hempstead has been calculated here.
Air line (approximately)
16 kilometers
9 nautical miles