The calculated distance (air line) between An Muileann gCearr and Sallins is approximately 34 miles respectively 54 kilometers.
By car or train, the actual journey to Sallins is certainly longer, as only the direct route (as the crow flies) between An Muileann gCearr and Sallins has been calculated here.
Air line (approximately)
54 kilometers
29 nautical miles