Pool Calculator

Finding the volume of a pool is a simple matter of getting the area of the surface of the pool and then multiplying that by the average depth.

• Start by entering the pool size (length and width).
• Then add its depth at the two endpoints.
• If there is both a shallow and a deep end, enter the shallow depth in the first field and the deepest point in the second. Otherwise, enter two identical values.
• If the depth of your pool changes drastically instead of gradually, you may want to consider dividing it in half, with a separate pool calculator measurement for each part (as in the image on the right).

You could go one step further and, knowing the density of water (which is approximately 1 kilogram per liter), work out how much the water in such a pool would weigh.

So you no longer need to worry “how many gallons is my pool?,” simply apply one of the formulas:

1. Rectangular/square pool

where:

• $V$ – Pool volume;
• $l$ – Length of the pool;
• $w$ – Width of the pool;
• 𝑑1d1​ – Depth at one end of the pool; and
• 𝑑2d2​ – Depth at another end of the pool.

The first two agents are, of course, the formula for the area of the rectangle.

2. Oval/circle pool

The first part of the equation comes from a standard area of an ellipsis formula: $A=\pi \times a\times b$, where $a$, $b$ are the distances between the center and the ellipse’s vertex, lying on the horizontal and vertical axes. In our case, we have the length and width values that are the doubled distances where $a$ and where $b$, so in the final formula, we need to divide the surface area of an oval by 4.

You are wondering why we average the depths 𝑑1+𝑑222d1​+d2​​? Have a look at the pictures:

1. Here you have the standard rectangular pool.

2. Let’s take the right trapezoidal side of the pool. “Cut” the triangle, with one apex in the midpoint of the side, as in the picture.
3. Flip and move it to the other side to form a rectangle. The edge of the new shape is the average of two sides, so 𝑑1+𝑑222d1​+d2​​.

The area of such a rectangle is then 𝑙×𝑑1+𝑑22l×2d1​+d2​​. Multiply it by the third dimension – the width – and you’ll get the final formula for rectangular pool volume:

Let’s calculate it with this pool volume calculator!

1. Choose the shape of your pool. You can select between two types – rectangular/square pool or oval/circle one. Our example is with a standard rectangular pool, so leave the default value.
2. Enter the dimensions of the swimming pool. Let’s say that the pool is 12 ft wide and 50 ft long. Depth is gradually changing from 4 to 6 feet.
3. The pool calculator shows the volume of water needed to fill up the pool. In our case, it’s 22,441.57 US gallons.

Our tool is sometimes called the pool size calculator or pool gallon calculator because it works with any unit, not just with metric units. If we didn’t auto-detect your preferred units, click on the unit to select from a range of available units.

4. If you know the price of water in your area, you can calculate the cost of filling up your pool. Click on the Water cost heading, and an additional part will appear. The pool gallon calculator takes the result of the previous section and multiplies it by the applicable rates of your local water supply. And that’s all you need to do to find out how much beating the heat will cost!Let’s take the average cost of water in the US, which is $1.50 per 1000 gallons. For our exemplary pool, the cost of water is $33.66. Not so bad, huh?

This calculator finds the total volume of your pool – in reality, you never fill the pool all the way to the brim.