Pond Volume Calculator

About this calculator

A backyard or garden pond's water volume is estimated by multiplying its surface length, width and average depth, then applying a shape factor that corrects for the fact that most ponds aren't perfect rectangular tanks — an irregular or sloped-edge pond might only hold 60–80% of the volume a straight box would. This calculator applies that correction and returns the result in cubic metres, liters and US gallons so you can work with whichever unit your equipment specifies.

Getting the volume right matters most to pond keepers, koi hobbyists and landscapers, who use it to size a pump or filter (rated in gallons/liters per hour relative to total volume), calculate correct dosing for algaecide, dechlorinator or fish medication, and estimate how much water a top-up or full water change will need. Aquatic garden designers also use rough volume estimates early in a build to plan liner size and stocking density for fish.