Long Lake is located at 42°22'14" North, 88°7'38" West (42.370833, -88.127500).
According to the United States Census Bureau, the city has a total area of 1.66 mi2 (4.29 km2). 1.05 mi2 (2.72 km2) of it is land and 0.61 mi2 (1.57 km2) of it is covered by water. The total area is 36.56% water.
Long Lake is located in the Central Standard Time (CST) timezone, GMT-06:00. It observes Daylight Saving Time (DST).