Pond Volume and Liner Calculator

Pond gallons, liner size and pump flow for a rectangular or oval garden pond.

Project Details
Enter your measurements and requirements
$
Results
Calculated estimates for your project
Volume1,436 gal
Weight of water11,978 lb
Liner size22 x 18 ft
Pump, one turnover per hour1,436 GPH
Soil to dig7.1 cu yd
Liner cost$396

Turn these numbers into a build plan.

  • 1,436 gal volume
  • 22 x 18 ft liner
  • $704 est. cost
Materials List
Recommended materials and quantities
Pond liner22 x 18 ft

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Project plan · built from your numbers

Garden pond, 1,436 gallons

12 x 8 ft pond with a 22 x 18 ft liner.

Materials
$704
Time
1 weekend
Level
Intermediate
5 steps 4 tools 3 materials
  1. 1

    Plan and call 811

    Mark utilities and check whether local rules cover ponds of this depth.

    • Utilities marked
  2. 2

    Dig in tiers

    Dig shelves down to 3 ft and move about 7.1 cu yd of soil.

    • Shelves cut
  3. 3

    Level the rim

    Level the edge all the way around.

    • Rim level
01 · Your numbers
Volume
1,436 gal
Liner
22 x 18 ft
Est. cost
$704
02 · The plan

5 steps · 4 tools · 3 materials

2 more steps, the full tool list and a shopping list you can check off as you go.

03 · Finished

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Garden pond, 1,436 gallons

Finished in 1 weekend · $704 DIY

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How to calculate pond volume and liner size

Use the average depth for gallons and the deepest point for the liner.

  1. Measure the surface. Length x width, or x 0.785 for an oval.
  2. Average the depth. Sample depths across the pond.
  3. Convert. Cubic feet x 7.48 = gallons.
  4. Size the liner. Add twice the deepest depth and 2 ft of overlap to each dimension.
  5. Size the pump. Plan to move the whole volume about once an hour.

Pond size examples at 2 ft average depth

PondGallonsLiner
6 x 4 ft35916 x 14 ft
10 x 6 ft89820 x 16 ft
12 x 8 ft143622 x 18 ft
16 x 10 ft239426 x 20 ft

Frequently asked questions

How do I calculate gallons in a pond?

Length x width x average depth in feet x 7.48. Multiply by 0.785 for an oval.

What size liner do I need?

Length plus twice the deepest depth plus 2 ft overlap, and the same for width.

What size pump?

About one full turnover an hour, or more for waterfalls.

How deep should a pond be for fish?

2 to 3 ft is common. Cold climates need enough depth to stay unfrozen below.

Do ponds need a permit or fence?

It depends on depth and local rules. Ask your local building department.

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