How it works
Pick the shape that best matches your pond and enter its dimensions and average depth. The calculator converts cubic feet to US gallons (7.48 gallons per cubic foot) and suggests a pump flow rate.
Most ponds have plant shelves and sloped sides, so use the average depth, not the deepest point. Take readings every couple of feet and average them. Irregular or kidney ponds are estimated at 85% of the surrounding rectangle.
Knowing the volume matters for dosing treatments, sizing pumps and filters, and stocking fish. A common guideline is to circulate the full volume at least once an hour, twice for koi, with a filter rated for at least the pond volume.
Formula
Rectangle: L × W × D × 7.48. Round: π × (diameter ÷ 2)² × D × 7.48. Irregular: L × W × D × 0.85 × 7.48. Gallons per hour = gallons × turnovers.
Questions people ask
How many gallons are in a cubic foot?
About 7.48 US gallons. A cubic foot of water weighs about 62.4 lb.
What size pump do I need for my pond?
Enough to move the full volume at least once per hour at your actual head height (vertical lift plus pipe friction). For a 1,200 gallon goldfish pond that is about 1,200 GPH delivered; koi ponds benefit from twice that.
How deep should a koi pond be?
At least 3 feet, and deeper in cold climates so fish can overwinter below the ice. Goldfish and plant ponds can be 18 to 24 inches.
How can I measure pond volume exactly?
Note the water meter reading before and after filling. Meter readings in cubic feet multiply by 7.48 for gallons.