The calculated distance (air line) between Chalfont St Giles and Beaconsfield is approximately 4 miles respectively 6 kilometers.
By car or train, the actual journey to Beaconsfield is certainly longer, as only the direct route (as the crow flies) between Chalfont St Giles and Beaconsfield has been calculated here.
Air line (approximately)
6 kilometers
3 nautical miles