Mermentau is a city located in Acadia Parish Louisiana. With a 2020 population of 621, it is the 204th largest city in Louisiana and the 12389th largest city in the United States . Mermentau is currently declining at a rate of -0.64% annually and its population has decreased by -6.05% since the most recent census, which recorded a population of 661 in 2010. Mermentau reached it's highest population of in . Spanning over 2 miles, Mermentau has a population density of 291 people per square mile.
The average household income in Mermentau is $46,981 with a poverty rate of 23.85%. The median rental costs in recent years comes to $275 per month, and the median house value is $79,700. The median age in Mermentau is 38.2 years, 40.4 years for males, and 35.5 years for females.