New Post is located at 45°53'44" North, 91°11'8" West (45.895556, -91.185833).
According to the United States Census Bureau, the city has a total area of 27.43 mi2 (71.03 km2). 20.36 mi2 (52.74 km2) of it is land and 7.06 mi2 (18.29 km2) of it is covered by water. The total area is 25.75% water.
New Post is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).