Mermentau is a city located in Louisiana. With a 2020 population of 619, it is the 208th largest city in Louisiana and the 12407th largest city in the United States. Mermentau is currently declining at a rate of -1.43% annually and its population has decreased by -6.35% since the most recent census, which recorded a population of 661 in 2010. Mermentau reached it's highest population of 661 in 2010. Spanning over 2 miles, Mermentau has a population density of 290 people per square mile.
The average household income in Mermentau is $45,443 with a poverty rate of 30.29%. The median rental costs in recent years comes to - per month, and the median house value is $74,400. The median age in Mermentau is 37.6 years, 37.8 years for males, and 37 years for females. For every 100 females there are 115.1 males.