Charleston is located at 40°27'57" North, 111°28'9" West (40.466111, -111.469167).
According to the United States Census Bureau, the town has a total area of 1.87 mi2 (4.84 km2). 1.68 mi2 (4.34 km2) of it is land and 0.19 mi2 (0.50 km2) of it is covered by water. The total area is 10.30% water.
Charleston is located in the Mountain Standard Time (MST) timezone, GMT-07:00. It observes Daylight Saving Time (DST).