Estimate swimming pool capacity in US gallons, imperial gallons, litres and cubic metres. Choose your pool shape, enter waterline dimensions and average water depth, and see a clear volume estimate.
Choose the pool shape and measurement unit, enter your dimensions and calculate the estimated water capacity.
Enter the pool's inside waterline dimensions and water depth. Use the actual water depth, not the wall height.
Pool shape
For a rectangle, measure length and width across the waterline.
Estimate only: steps, ledges, shelves and irregular floor profiles can affect real capacity.
Follow these steps to measure your pool, estimate average water depth, and convert the volume into gallons or litres.
Measure the inside waterline length and width. For a round pool, enter its diameter; for an oval or kidney-shaped pool, use the available width measurements.
Select the shape that most closely matches your pool and use feet or metres consistently for all dimensions.
Add shallow-end and deep-end water depths, then divide by two for an approximate average depth on a reasonably even slope.
Read the estimated US gallons, imperial gallons, litres and cubic metres, along with the formula used.
Pool capacity is estimated from the pool footprint area multiplied by average water depth. The exact area formula depends on the pool shape.
Volume (ft³) = length × width × average depth
US gallons = cubic feet × 7.48052
Volume = π × (diameter ÷ 2)² × average depth
Volume = (π ÷ 4) × length × width × average depth
Approximate volume (ft³) = 0.45 × length × (width A + width B) × average depth
The kidney-shape factor is a rough estimate. For complex freeform outlines, split the pool into simpler shapes and add their volumes.
Average depth ≈ (shallow-end depth + deep-end depth) ÷ 2. For metre measurements, convert the calculated volume to cubic metres; 1 m³ = 1,000 litres.
Use consistent units and treat these formulas as estimates. Steps, ledges, shelves and irregular floor profiles can change the actual capacity.
The total amount of money borrowed or the remaining balance of the loan before interest is added.
The monthly interest rate, calculated by dividing the annual nominal interest rate by 12.
The total count of periodic payments required to fully pay off the loan term (e.g., 360 payments for 30 years).
The calculated final amount you can expect to pay each month, combining both principal amortization and accrued interest.
These examples show how pool dimensions and average depth affect estimated water capacity.
A pool 30 ft long and 15 ft wide with 5 ft average water depth.
Given: Length 30 ft, width 15 ft, average depth 5 ft
Calculation:
30 × 15 × 5 = 2,250 cubic feet
2,250 × 7.48052 ≈ 16,831 US gallons
Answer: Approximately 16,831 US gallons
A round pool with a 20 ft diameter and 4 ft average water depth.
Given: Diameter 20 ft, average depth 4 ft
Calculation:
π × 10² × 4 ≈ 1,256.64 cubic feet
1,256.64 × 7.48052 ≈ 9,399 US gallons
Answer: Approximately 9,399 US gallons
An oval pool with a 24 ft long axis, 12 ft short axis and 4.5 ft average water depth.
Given: Length 24 ft, width 12 ft, average depth 4.5 ft
Calculation:
(π ÷ 4) × 24 × 12 × 4.5 ≈ 1,017.88 cubic feet
1,017.88 × 7.48052 ≈ 7,614 US gallons
Answer: Approximately 7,614 US gallons
Answers to common questions about pool measurements, volume formulas, gallon conversions and estimate accuracy.
For a rectangular pool measured in feet, multiply length × width × average water depth to get cubic feet. Multiply that result by 7.48052 to estimate US gallons.
Add the shallow-end water depth and deep-end water depth, then divide by two. This is a useful approximation for a reasonably even slope; split pools with shelves or abrupt depth changes into separate sections.
One US liquid gallon is approximately 3.78541 litres. One imperial gallon is approximately 4.54609 litres, so make sure you use the correct gallon unit.
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CalcNova was created and is maintained collaboratively by two friends who want to make everyday calculations simpler and more accessible. We build practical online calculators and clear explanations to help people understand results and the methods behind them.
Our focus is on clear formulas, useful examples, and regularly maintaining our tools. Calculator results are intended for guidance; for important financial decisions, confirm figures with the relevant provider or a qualified professional.