View a list of Zip Codes in Puerto RicoThe average area for zip codes in Puerto Rico is 65.5 km² with the largest being 00641 in Utuado, Utuado Municipio at 245.7 km² and the smallest being 00906 in San Juan, San Juan at 8,204 m². In Puerto Rico the average population for a postal code is 28,119 with the most populated being zip code 00926 in San Juan, San Juan at 105,261. The median age for postal codes in Puerto Rico range from 31.7 years old for 00925 in San Juan, San Juan to 52.1 years old for 00968 in Guaynabo, Guaynabo Municipio. The fastest growing postal code is 00778 in Gurabo, Gurabo Municipio with population growth of 36.1% from 2000 to 2015, an average of 2.1% per year.