The calculated distance (air line) between Santa Lucía Cotzumalguapa and Retalhuleu is approximately 46 miles respectively 74 kilometers.
By car or train, the actual journey to Retalhuleu is certainly longer, as only the direct route (as the crow flies) between Santa Lucía Cotzumalguapa and Retalhuleu has been calculated here.
Air line (approximately)
74 kilometers
40 nautical miles