Why does the irregular shape use a 0.75 factor?

Irregular ponds are rarely rectangular boxes. The 0.75 multiplier is a widely used field approximation that accounts for sloping sides and uneven bottoms. For precise results, measure several depth points and use their average.

How many gallons per inch of fish should I stock?

A common rule of thumb is 10 US gallons of pond water per 1 inch of fish body length. For koi, many keepers use 250–500 gallons per fish due to their larger adult size and waste output.

What units should I enter dimensions in?

Enter all dimensions in feet or all in meters — the calculator keeps a consistent unit throughout. Switch between feet and meters using the unit toggle, and the result updates instantly.

Why is there a depth multiplier for circular and oval ponds?

Lined ponds are rarely perfectly vertical-sided; they taper toward the bottom. A depth factor of 0.9 is applied by default for circular and oval shapes to reflect the common bowl-like cross section.

Can I use this for a raised pond or a container water garden?

Yes. Use the rectangular shape for square or box containers, circular for barrel ponds or round tubs. Just measure inner dimensions and enter actual water depth, not the container height.

Pond Volume Calculator

Name: Pond Volume Calculator
Availability: InStock
Author: Nham Vu

Enter your pond dimensions and shape to get the water volume in gallons and liters instantly.

Pond Dimensions

Units:

Pond Shape

Pond Volume

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US Gallons

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Liters

Enter pond dimensions to see the volume

Summary

Enter your pond dimensions and shape to get the water volume in gallons and liters instantly.

How it works

Select your pond shape: rectangular, circular, oval, or irregular.
Enter the required dimensions for that shape (length, width, depth, or radius).
For irregular ponds, enter an average length, average width, and average depth.
The calculator applies a shape factor and displays volume in US gallons and liters.
Use the result to calculate treatment doses or estimate fish stocking levels.

Use cases

Calculating the correct dose of algaecide or pond treatment chemical.
Estimating how many goldfish or koi a pond can support.
Sizing a water pump or filter system by total pond volume.
Figuring out how long a hose will take to fill or refill the pond.
Planning water changes for fish health in a garden pond.
Checking whether a new pond design meets a target volume.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu