Au Gres is a city located in Arenac County, Michigan. As of the 2000 census, the city had a total population of 1,028.
According to the United States Census Bureau, the city has a total area of 6.2 km2 (2.4 mi2). 5.9 km2 (2.3 mi2) of it is land and 0.2 km2 (0.1 mi2) of it is water. The total area is 3.78% water.