Round Rock is located at 30°30'28" North, 97°40'42" West (30.507778, -97.678611).
According to the United States Census Bureau, the city has a total area of 26.26 mi2 (68.02 km2). 26.14 mi2 (67.69 km2) of it is land and 0.13 mi2 (0.33 km2) of it is covered by water. The total area is 0.48% water.
Round Rock is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).