Zip code 93401 statistics: (Find on map). Estimated zip code population in 2011: 27,618. Zip code population in 2010: 28,033. Zip code population in 2000: 27,034. Mar. 2012 cost of living index in zip code 93401: 108.4 (more than average, U.S. average is 100). Land area: 69.9 sq. mi.Water area: 0.0 sq. mi.he number of registered sex offenders compared to the number of residents in this zip code is a lot smaller than the state average. Back to: San Luis Obispo, CA, All cities. Back to the top. Home price trends powered by Onboard Informatics. © 2012 Onboard Informatics.