Ontario, CA has a population of 169,389 and is the 150th largest city in the United States. The population density is 3,392 per sq mi which is 1360% higher than the California average and 3644% higher than the national average. The median age in Ontario is 32 which is approximately 11% lower than the California average of 36. In Ontario, 50% of the population over 15 years of age are married, 41% speak English and 53% speak Spanish. 61% of Ontario residents were born in California, 9% were born out of state, 1% were born outside of the United States and 29% were foreign born.