Duncanville is located at 32°39'6" North, 96°54'29" West (32.651667, -96.908056).
According to the United States Census Bureau, the city has a total area of 11.29 mi2 (29.24 km2). 11.29 mi2 (29.23 km2) of it is land and 0.00 mi2 (0.01 km2) of it is covered by water. The total area is 0.02% water.
Duncanville is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).