The calculated distance (air line) between Newtown Trim and Dún Laoghaire is approximately 32 miles respectively 51 kilometers.
By car or train, the actual journey to Dún Laoghaire is certainly longer, as only the direct route (as the crow flies) between Newtown Trim and Dún Laoghaire has been calculated here.
Air line (approximately)
51 kilometers
28 nautical miles