Lake Forest, CA has a population of 80,658 and is the 429th largest city in the United States. The population density is 4,849 per sq mi which is 1987% higher than the California average and 5252% higher than the national average. The median age in Lake Forest is 39 which is approximately 8% higher than the California average of 36. In Lake Forest, 60% of the population over 15 years of age are married, 69% speak English and 17% speak Spanish. 53% of Lake Forest residents were born in California, 22% were born out of state, 2% were born outside of the United States and 23% were foreign born.