CalcCommonsHow to use
Select the plan shape and measurement unit. Enter inside dimensions and the shallow and deep water depths. Choose the output unit you need; the other volume conversions remain visible for comparison.
For related tasks, try the Volume Calculator.
Formula & how it works
Volume = plan area × average water depth. Rectangle: area = L × W. Circle: area = πD² / 4. Ellipse: area = πLW / 4. For a uniform bottom slope, average depth = (shallow + deep) / 2. 1 US gallon = 3.785411784 liters.
Worked examples
Example 1
A 24 × 12 ft rectangular pool with a uniform slope from 3 to 5 ft water depth averages 4 ft deep. Volume is 1,152 ft³, approximately 8,617.56 US gallons.
Example 2
A round pool 4 m in diameter with a flat 1.2 m water depth holds π × 2² × 1.2 ≈ 15.08 m³, or about 15,080 liters. Enter 1.2 in both depth fields.
Assumptions & practical notes
Measure inside the pool at the intended water level. Wall height includes freeboard and overstates water depth.
Averaging endpoint depths is appropriate only for a uniform slope across the plan. For shelves, deep wells, steps or irregular shapes, calculate separate regions and add the volumes.
An oval here is a mathematical ellipse. A stadium-shaped pool with straight sides and semicircular ends requires separate rectangle and circle calculations. Volume is not chemical-dosing advice.
See our calculation methodology for unit definitions and testing practices.
Results are estimates for planning purposes. Verify measurements, product specifications, and applicable building codes before purchasing materials or starting work.
References & measurement guidance
Use the instructions for your selected product and the requirements that apply to your project. Example inputs are not universal specifications.
Frequently asked questions
Why do gallons differ from another estimate?
Some shortcuts use rounded constants such as 7.5 gallons per cubic foot. This tool uses exact unit definitions and π; different shape or depth assumptions can create larger differences.
Are these US or Imperial gallons?
The gallon result is US liquid gallons. Use liters when a product label uses metric volume.
How do I enter a flat-bottom pool?
Use the same water depth for shallow and deep. The average will equal that depth.
Can I estimate an irregular pool?
Divide it into simple regions with representative water depths, calculate each separately and add the volumes. Do not expect one bounding rectangle to describe a freeform pool accurately.
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