Casper is located at 42°51'59" North, 106°18'45" West (42.866389, -106.312500).
According to the United States Census Bureau, the city has a total area of 24.26 mi2 (62.84 km2). 23.95 mi2 (62.02 km2) of it is land and 0.32 mi2 (0.82 km2) of it is covered by water. The total area is 1.30% water.
Casper is located in the Mountain Standard Time (MST) timezone, GMT-07:00. It observes Daylight Saving Time (DST).