How do you determine the number of gallons of water in a round pool 25ft x 4ft?

The calculation for a ROUND pool is:

Diameter x Diameter x Depth X 5.9 = Number of Gallons

For example:

For example, the volume of a 15-foot round pool with an actual water depth of 3 ft is: 15x15x3x5.9 = 3,982 gallons.

Please note that the DEPTH is the ACTUAL water depth NOT the height of the pool wall (the water is usually around 6 inchs lower than the wall height).

Hope this helps ...

http://www.poolspa.com/calculator/