Calculating surface area and gallons of water in a pool or spa

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There are times when it is necessary to know the surface area and the volume of water of your swimming pool or spa, especially when adjusting the pool chemical balance of the water. (...So many ounces per gallon of water)

To determine the approximate number of gallons or liters in your swimming pool or spa, first determine the surface area. Then multiply the area by the average depth and the constant conversion factor of 7.5 to convert cubic feet to gallons (for every cubic foot of water there are 7.5 gallons of water) or 1000 to convert cubic meters to liters (for every cubic meter of water, there are 1000 liters of water). To find the average depth for a more complex shaped pool, divide the complex shape into several simple shapes. Calculate each one separately, and add them back together. For circular shapes, R stands for the radius.

Here are some simple calculations to work with:

Rectangle: AREA = L X W;

(average depth = depth 1 + depth 2 divided by 2) OR (D1 + D2) / 2 = AVE. DEPTH

GALLONS = AREA X AVE. DEPTH X 7.5

LITERS = AREA X AVE. DEPTH X 1000

Oval: AREA = A(short radius) X B(long radius) X 3,14

GALLONS = AREA X AVE. DEPTH X 7.5

LITERS = AREA X AVE. DEPTH X 1000

Circle: AREA = R X R X 3.14

GALLONS = AREA X AVE. DEPTH X 7.5

LITERS = AREA X AVE. DEPTH X 1000

Of course the more complex the shape of your swimming pool, the more complex the formula, but you should be able to divide the entire shape into these smaller shapes.

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