Pool Volume Calculator
Estimate rectangular or circular pool volume in US gallons, liters and cubic feet from length, width, diameter and average depth. Includes sloped-floor tips.
Results
Gallons (US)
Liters
- Cubic feet
- 2,250
You might also need
Educational estimates · not financial advice · free, no signup
Formula / how it works
Rect: L×W×D cu ft × 7.48052 = gallons. Circle: πr²×depth.
Detailed guide
What it is, how to use it, how to read the numbers, common mistakes, a worked example, formulas, and FAQs.
What this calculator is
Knowing how much water your pool holds is essential for dosing chemicals, sizing a pump and heater, and estimating fill cost. This calculator computes volume for rectangular and circular pools from length, width or diameter and the average depth, then converts cubic feet into US gallons and liters. For pools with a sloped floor, use the average of the shallow and deep ends. Irregular shapes such as kidney or free-form pools need a more careful approach, such as splitting the pool into simple sections, because a single rectangle or circle will not be accurate.
When to use / who it helps
- You are adding chemicals and need the right volume to dose.
- You are choosing a pump, heater or cover.
- You want to estimate filling cost or time.
- You are buying an above-ground pool and want to compare sizes.
- You are draining and need to know the volume to remove.
How to use
Steps
- Select the shape, rectangular or circular.
- For a rectangle, enter length and width in feet.
- For a circle, enter the diameter in feet.
- Enter the average depth: shallow depth plus deep depth divided by two for a sloped floor.
- Read the volume in US gallons, liters and cubic feet.
- Reduce slightly if you fill below the top.
How to interpret results
- One cubic foot is 7.48052 US gallons.
- Volume depends linearly on depth, so an error in average depth causes the same percentage error in volume.
- Water weighs about 8.34 lb per US gallon, so large pools weigh tens of tons.
- Operating water level is usually below the rim, lowering effective volume.
- Free-form pools need sectioned estimates.
Common mistakes & gotchas
- Using maximum depth instead of average depth.
- Using the diameter as a radius.
- Mixing feet and meters.
- Forgetting the unusual shape of the pool.
- Using US gallons where imperial gallons are expected.
Worked example
Worked example — 30 ft × 15 ft pool with an average depth of 5 ft
- Volume: 30 × 15 × 5 = 2,250 cubic feet.
- Gallons: 2,250 × 7.48052 ≈ 16,831 US gallons.
- Liters: 16,831 × 3.785412 ≈ 63,713 L.
- A circular pool 24 ft across and 4 ft average depth: π × 12² × 4 ≈ 1,809.6 ft³, or about 13,536 gallons.
Result: About 16,831 US gallons (63,713 liters) for the rectangular pool.
To load the form's own demo values, tap Try example above the Calculate button.
How to calculate / formula
Rect: L×W×D cu ft × 7.48052 = gallons. Circle: πr²×depth.
Frequently asked questions
How do I find average depth?
Add the shallow and deep end depths and divide by two for a steady slope.
How many gallons are in a cubic foot?
7.48052 US gallons.
How much does pool water weigh?
About 8.34 pounds per US gallon, so the example pool holds roughly 140,000 pounds.
What about oval or kidney pools?
Approximate them with sections or use the manufacturer's volume.
Why do I need pool volume?
Chemical dosing, pump sizing and fill cost all depend on it.
Is this for imperial gallons?
No. It reports US gallons; an imperial gallon is about 20% larger.