How can you know the volume of water in a swimming pool with rectangular shape?

If the pool is rectangular in shape then the formula is:

length X width x average depth x 7.5.

If the pool is circular then the formula is:

3.14 x 3.14 x pool radius (1/2 pool diameter) x average depth x 7.5.

If the pool has a shape other than these then it is a little more difficult.

For round pools you want the area of the circle x the height, or 3.14 x radius x radius x height, then convert feet to gallons by x 7.5.

A 24 foot by 4 feet deep pool holds 13,564 gallons.