Granite Bay is located at 38°44'54" North, 121°10'47" West (38.748504, -121.179793).
According to the United States Census Bureau, the city has a total area of 21.66 mi2 (56.10 km2). 21.58 mi2 (55.90 km2) of it is land and 0.07 mi2 (0.19 km2) of it is covered by water. The total area is 0.34% water.
Granite Bay is located in the Pacific Standard Time (PST) timezone, GMT-08:00. It observes Daylight Saving Time (DST).