Costa Mesa, CA has a population of 112,439 and is the 252nd largest city in the United States. The population density is 7,151 per sq mi which is 2977% higher than the California average and 7793% higher than the national average. The median age in Costa Mesa is 35 which is approximately 4% lower than the California average of 36. In Costa Mesa, 47% of the population over 15 years of age are married, 61% speak English and 29% speak Spanish. 56% of Costa Mesa residents were born in California, 18% were born out of state, 1% were born outside of the United States and 25% were foreign born.