Water & Containers
Pool Volume Calculator
Estimate pool capacity from shape and depth, with a linear shallow-to-deep option.
Enter your measurements
Results update as you type.
About this calculator
Enter a rectangular, circular or elliptical pool with a constant depth or a linear shallow-to-deep slope. Capacity is shown in cubic metres, litres, US gallons, imperial gallons and cubic feet — US and imperial gallons are always labeled distinctly.
How to use this calculator
- Pick the pool shape and measure its dimensions.
- Choose constant depth or a linear slope and measure the depth(s).
- Calculate.
- Read capacity in litres, US gallons and imperial gallons.
Formula
Area = L × W (rectangle), π d² ÷ 4 (circle), π L W ÷ 4 (ellipse)
Average depth = (shallow + deep) ÷ 2 for a linear slope
Volume = area × depth; 1 m³ = 1000 L exactly; 1 US gal = 231 in³; 1 imp gal = 4.54609 L
Assumptions
- A linear slope averages the two end depths exactly.
- Internal (water) dimensions — wall thickness is not part of a pool measurement here.
- US gallon and imperial gallon are separate units and are labeled every time.
Water-volume conversion reference
| Unit | Litres |
|---|---|
| 1 US gallon | 3.785411784 L |
| 1 imperial gallon | 4.54609 L |
| 1 cubic metre | 1,000 L |
Exact unit definitions. Irregular pool geometry is still an approximation.
Common mistakes
- Measuring outside dimensions instead of the water-holding space.
- Using a shallow/deep average for a profile with shelves or irregular slopes.
- Confusing US gallons and imperial gallons.
Worked example
Try it: press “Load example” above the form.
A 10 × 5 m pool sloping 1 m to 2 m averages 1.5 m deep — 75 m³ = 75,000 L = 19,813 US gal.
Limitations
No dosing, treatment, safety or circulation-rate advice. Capacity math only.
Frequently asked questions
Which depth should I use for a sloping pool?
Use a representative average water depth for the shape the calculator models. A simple average of shallow and deep depths only fits a consistently sloping profile. Steps, shelves and irregular slopes need separate sections.
Are US and imperial gallons the same?
No. A US gallon is exactly 3.785411784 litres; an imperial gallon is exactly 4.54609 litres. Select the labelled unit rather than assuming every gallon value is interchangeable.
What does the worked example show?
A 10 × 5 m pool sloping 1 m to 2 m averages 1.5 m deep — 75 m³ = 75,000 L = 19,813 US gal.
Which assumptions should I check before using the result?
No dosing, treatment, safety or circulation-rate advice. Capacity math only.
Sources
Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.
Calculation documentation · Updated 2026-11-08 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.
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