San Ardo, CA has a population of 821 and is the 16,430th largest city in the United States. The population density is 1,827 per sq mi which is 686% higher than the California average and 1917% higher than the national average. The median age in San Ardo is 25 which is approximately 30% lower than the California average of 36. In San Ardo, 45% of the population over 15 years of age are married, 22% speak English and 77% speak Spanish. 61% of San Ardo residents were born in California, 5% were born out of state, 1% were born outside of the United States and 33% were foreign born.