New pond owners are unsure of where to start when it comes to finding the volume of water in their pond. When you buy a container of algaecide, beneficial bacteria, or any other water treatment supply, you’ll see suggestions for dosing. Getting a closer estimate of the volume of your pond helps you with proper dosing to keep fish safe and to avoid wasting any supplies. We are asked how to do this often, so I put this article together to help you get a better understanding of how to calculate the number of gallons of water for differently shaped ponds.

To figure out the volume of your pond, all you are going to need is a tape measure and one of the following equations below.

How Do You Average Different Parts Of The Pond?

To calculate the length, width, or depth of the pond, you will need to take the average of each. Let’s take finding the Average Length of a pond. It’s best to measure the length at least 3 different times. You can measure as many times as you want for the length, width, or depth as long as you find an average, but 3 times usually gets you pretty close.

Take the average of Length, Width, and Depth. There is an example of how to find the Average Depth below:

For Rectangle Shaped Ponds

All you have to do to find the Volume of a rectangular shaped pond is take the averages of the length, width, and depth, then multiply them by the number 7.48. There is an example and an image below. Even if your pond isn’t exactly a rectangle, this is the most common method of finding the gallons of water in a pond.

AVG Length (12 feet) x AVG Width (10 feet) x AVG Depth (2.5 feet) x 7.48 = 2,244 Volume in Gallons

For Circular Shaped Ponds

Finding the Volume of water in a circular shaped pond has one extra step. First, you’re going to find the “Cubic Feet” of the pond. Then you take that number and multiply it by 7.48. That will give you the number of gallons of water in your pond. See the example below to get a better idea of how to go about this.

Step 1:

Radius 1 (4 feet) x Radius 2 (7 feet) x 3.14 x AVG Depth (2 feet) = 175.84 Cubic Feet

Step 2:

Cubic Feet (175.84) x 7.48 = 1,315 Volume in Gallons

Finding the volume of water in a pond is never an exact science. Your goal is to get as close as you reasonably can. This will help you with dosing water treatment supplies, which will be safer for fish, wildlife, and the quality of the water.