The calculated distance (air line) between Sutton and Dún Laoghaire is approximately 7 miles respectively 11 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Sutton and Dún Laoghaire has been calculated here.
Air line (approximately)
11 kilometers
6 nautical miles