The calculated distance (air line) between Leighton Buzzard and Hemel Hempstead is approximately 14 miles respectively 23 kilometers.
By car or train, the actual journey to Hemel Hempstead is certainly longer, as only the direct route (as the crow flies) between Leighton Buzzard and Hemel Hempstead has been calculated here.
Air line (approximately)
23 kilometers
12 nautical miles