Brentwood, TN has a population of 40,873 and is the 1,008th largest city in the United States. The population density is 992 per sq mi which is 548% higher than the Tennessee average and 995% higher than the national average. The median age in Brentwood is 41 which is approximately 8% higher than the Tennessee average of 39. In Brentwood, 74% of the population over 15 years of age are married, 91% speak English and 2% speak Spanish. 41% of Brentwood residents were born in Tennessee, 49% were born out of state, 1% were born outside of the United States and 9% were foreign born.