The calculated distance (air line) between Kilcock and Dún Laoghaire is approximately 23 miles respectively 38 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Kilcock and Dún Laoghaire has been calculated here.
Air line (approximately)
38 kilometers
20 nautical miles