How to Measure Your Pond or Lake

Knowing the size of your pond is essential for any pond or lake owner. Accurate pond size will help you effectively manage your pond, including determining dosage rates for chemicals and beneficial bacteria, properly sizing an aeration system, calculating how many fish to stock, and determining which fountain will make the most of your outdoor space.

Calculating pond size is not difficult, but it does require a few simple tools, the right equation, and a little work.

Calculate Size

Start by measuring your pond's length and width, which will help determine acreage. Rectangular ponds are easiest to measure, but you can figure out these numbers for a circular, triangular, or odd-shaped pond, too. Pace off (one step is about 3 feet) or use a measuring tape to get the numbers you need, and then plug them into one of these formulas:

Square/rectangle - Calculate the length and width; L x W = surface area
Circle - Calculate radius (1/2 of the pond length); Pi x R2 or 3.14 x R x R = surface area
Triangle - Calculate the base and height; (0.5 x B) X H = surface area
Odd-shaped - Measure your pond in sections using the calculations above or use an online tool like Google Maps

To determine how many acres your pond is, divide your value for surface area by 43,560 (the number of square feet per acre).

Determine Depth

Pond depth influences many decisions in pond and lake management. Many chemicals and natural water treatments require a depth measurement for accurate dosage. Aeration diffusers placed at deeper depths are more efficient at circulating the water and infusing it with oxygen. Additionally, decorative fountains have a minimum operating depth, so knowing this measurement is critical.

Depth can change over the years, and certain parts of your pond may be deeper than others. If you do not know your depth or think it may have changed, it is time to familiarize yourself with the bottom of your pond. Use these tips to figure out your pond's depth.

Start by grabbing a string marked in 1-foot intervals, a weight (like a brick), a notepad, a pencil, and a boat or canoe. Then head out to the pond, and follow these directions:

Securely attach the weight to one end of the string.
Gather your materials into your boat or canoe, and head toward the pond’s center.
Drop the weighted string into the pond and record the depth where it hit the bottom. Repeat in at least four other locations in the pond, more if your pond is huge.
When you have a good sampling of your pond's depth, record the maximum depth and calculate the average of the measurements you took.

Consider Shape

Ponds come in all shapes and sizes, adding to their beauty and interest, but can sometimes complicate your measurements and your choice of pond solutions.

The shape will affect aeration layouts. Ponds with an island, cove, irregular shorelines or other unique features require more diffusers than a uniformly shaped pond, as these features limit oxygenated water circulation. Breaking odd-shaped ponds into sections will help determine how many diffuser plates will be needed for the entire pond.

Pond shape may also influence fountain selection. Consider the height and width of your chosen spray pattern. You do not want the spray to hit any portion of the shoreline, affecting the fountain’s aesthetic and causing erosion.

Expert Help is Just a Phone Call Away

Feeling overwhelmed by accurately measuring your pond? We can help. At no cost or commitment to you, we’ll use our proprietary software to measure and analyze your pond accurately. We'll also connect you with one of our experts, who will help you with all your pond and lake needs.

Give us a call at (866) 424-7629, or fill out the contact form to get started.