Brentwood, PA has a population of 9,550 and is the 4,076th largest city in the United States. The population density is 6,598 per sq mi which is 2281% higher than the Pennsylvania average and 7182% higher than the national average. The median age in Brentwood is 37 which is approximately 10% lower than the Pennsylvania average of 41. In Brentwood, 52% of the population over 15 years of age are married, 92% speak English and 4% speak Spanish. 82% of Brentwood residents were born in Pennsylvania, 10% were born out of state, 1% were born outside of the United States and 7% were foreign born.