Calculating The Amount Of Water In Your Pool

How to Calculate the Amount of Water in your Swimming Pool

In Ask the Pool Experts by Swimming Pool Expert

It is essential to know the total amount of water in your swimming pool, to ensure you have the correct equipment and needed chemical amounts. 

When a pool owner knows the amount of water in their pool, it will be easier to do the proper maintenance. Knowing how many gallons of water are in your pool will help you to know how many chemicals and chlorine your pool will need. 

How to Calculate the Amount of Water in a Pool

Not everyone is a mathematician, but with following the formulas, calculating the number of gallons in your pool will come naturally. The calculations go according to the shape and measurements.

Square or Rectangle Pool

To calculate the number of gallons of water in a square or rectangular pool will depend if it is a constant depth or a variable depth.  

For example, if your pool has a constant depth, multiply it with the length and width of the oasis to get the total in cubic feet. Then, multiply the total measurements by 7.5 to calculate the sum in gallons.

Let’s say that the pool measures 18×36, and the constant depth is 5 feet, then this will be the formula:

36x18x5x7.5 = 24,300 Gallons

Most pools, however, have a variable depth. That means that the oasis has a shallow and deep end. To make the calculation, add the measurements of the shallow end to the deep end, and divide by two. This will give you the average depth.

If the shallow end is three feet, and the deep end is 10 feet deep, it will be thirteen feet average, then divided in two, the result should be 6.5 feet.

(3+10)÷2 = 6.5 feet (average depth)

Next multiply the pool’s length, width, average depth for the cubic feet, and then multiply by 7.5 for the total amount in gallons

36x18x6.5×7.5 = 31,590 Gallons

Round Pool

To calculate a round pool with a constant depth, all you must do is find its volume as if it were a cylinder.   Multiply the length and the depth and divide by two to get the result in diameter.

For example, the radius of the pool is 26 feet, divide the number by two:

26÷2 = 13

Next, multiply the same number:

13×13 = 169

Then proceed using this formula for the total gallons of water in a round oasis:

3.14 × r2 (169) × Depth (7) × 7.5 = 27,859.6 Gallons

Freeform Shaped Pool

It takes a bit more math to find the number of gallons in a uniquely designed pool.  A freeform-designed oasis has different measurements. Say that an oasis has different lengths and widths, if that’s the case then it’s just adding the lengths and widths take that total, divide it by the number of widths available.

For example, if there is a pool that has three widths: 25, 20, and 25, add them and then divide them by three:

25+15+25÷3 = 21.7 feet

The next step is to calculate the cubic feet of the pool. Once getting the total average width, multiply the totals of the depth and length to get the total in cubic feet.

Say that the pool is 35 feet long and the average depth is 6 feet, then the formula would be:

6×21.7×35 = 4,557 cubic feet

Finally, multiply the total in cubic feet by 7.5, and the result will be 34,178 gallons. 

Calculating the amount of water in a swimming pool will help a pool owner to know how much chlorine or other chemicals are needed to keep the oasis clean. However, if a client has an unusual shaped pool, our experts are ready to help you out.

Don’t forget that Summer’s around the corner. Platinum Pools is ready to help get your pool ready or built. Call us today at 281.870.1600 or visit our website for a free quote.