The calculated distance (air line) between Drogheda and An Muileann gCearr is approximately 43 miles respectively 69 kilometers.
By car or train, the actual journey to An Muileann gCearr is certainly longer, as only the direct route (as the crow flies) between Drogheda and An Muileann gCearr has been calculated here.
Air line (approximately)
69 kilometers
37 nautical miles