Seneca is located at 34°41'7" North, 82°57'11" West (34.685278, -82.953056).
According to the United States Census Bureau, the city has a total area of 7.09 mi2 (18.37 km2). 7.06 mi2 (18.27 km2) of it is land and 0.04 mi2 (0.10 km2) of it is covered by water. The total area is 0.54% water.
Seneca is located in the Eastern Standard Time (EST) timezone, GMT-05:00. It observes Daylight Saving Time (DST).