Greenfield is a city in Weakley County, Tennessee, United States. The population was 2,182 at the 2010 census and 2,078 in 2018. Greenfield is located at 36°9′25″N 88°48′5″W / 36.15694°N 88.80139°W. According to the United States Census Bureau, the city has a total area of 3.6 square miles, of which 3.6 square miles is land and 0.04 square miles is water.