Common rectangular in-ground pool sizes include 10 x 20, 15 x 30 and 20 x 40 feet; however they can be built to any shape or size. Homeowners should consider the intended use of the pool, who will be using it and the limitations of the space.
Pools used for lap swimming or exercise are best built long, while diving pools need to be deep. Recreational pools meant for occasional use while lounging in the backyard are smaller. The height and mobility of those using the pool are important considerations for the average depth and a beach entry versus stairs. The size of the pool will also come down to the total size of the yard and how much space homeowners wish to leave for other activities.