The calculated distance (air line) between Leighton Buzzard and Amersham on the Hill is approximately 17 miles respectively 27 kilometers.
By car or train, the actual journey to Amersham on the Hill is certainly longer, as only the direct route (as the crow flies) between Leighton Buzzard and Amersham on the Hill has been calculated here.
Air line (approximately)
27 kilometers
15 nautical miles