Half Moon Bay, CA has a population of 12,281 and is the 3,352nd largest city in the United States. The population density is 1,912 per sq mi which is 723% higher than the California average and 2010% higher than the national average. The median age in Half Moon Bay is 47 which is approximately 31% higher than the California average of 36. In Half Moon Bay, 61% of the population over 15 years of age are married, 68% speak English and 22% speak Spanish. 46% of Half Moon Bay residents were born in California, 27% were born out of state, 2% were born outside of the United States and 25% were foreign born.