Gallatin is located at 36°23'17" North, 86°26'47" West (36.388056, -86.446389).
According to the United States Census Bureau, the city has a total area of 22.46 mi2 (58.17 km2). 21.97 mi2 (56.91 km2) of it is land and 0.49 mi2 (1.26 km2) of it is covered by water. The total area is 2.17% water.
Gallatin is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).