Calculate how many gallons or litres of water a pool holds.
Calculated instantly in your browser.
How do you calculate the volume of a pool?
Rectangular pool: length × width × depth. Round pool: π × radius² × depth. Convert cubic feet to gallons using 1 ft³ = 7.48 US gallons. For example, a 32 ft × 16 ft pool with a 5 ft average depth holds about 19,150 US gallons. Use the average depth if the pool has a deep end, and dose chemicals accordingly.
Understanding your result
Knowing the volume lets you dose chlorine and other chemicals correctly. Use the average depth if the pool has a deep end.
Formula and method
Rectangular: length × width × depth. Round: π × radius² × depth. 1 ft³ = 7.48 US gallons.
Assumptions and limitations
The result assumes a regular shape and a single or average depth, so irregular, kidney or freeform pools are only approximated. Sloping floors, steps and built-in features change the true volume. Use it to guide chemical dosing and refills, but follow product instructions and test the water rather than relying on the figure alone.
Worked example
A 32 ft × 16 ft pool with a 5 ft average depth holds about 19,150 US gallons.
How to use this tool
- Choose the pool shape and units.
- Enter the dimensions and average depth.
- Press Calculate.
About the Pool Volume Calculator
The Pool Volume Calculator works out how much water a rectangular or round pool holds, in US gallons, imperial gallons and litres.
Who should use this tool
Pool owners and installers who need the water volume to dose chemicals, plan a refill or size equipment. Suits rectangular and round pools, and anyone wanting the capacity in US gallons, imperial gallons or litres for buying chlorine and other treatments.
Benefits
- Calculates volume for rectangular and round pools
- Shows US gallons, imperial gallons and litres
- Helps you dose chemicals more accurately
- Free in the browser with nothing to install
Practical use cases
- Working out capacity to dose chlorine correctly
- Estimating water needed to refill a pool
- Sizing a pump or filter to the volume
- Budgeting chemicals for the swimming season
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Frequently asked questions
How do I find the average depth?
Add the shallow-end and deep-end depths and divide by two for a flat-sloped pool.
How do I handle a pool with a deep end?
Use the average depth rather than a single figure. For a floor that slopes evenly, add the shallow and deep depths and divide by two. This gives a close estimate for a standard pool, though very irregular profiles will differ, so treat the volume as a good working figure.
Why do I need to know my pool's volume?
Nearly every pool chemical is dosed by water volume, so an accurate figure keeps chlorine, pH adjusters and other treatments in the safe, effective range. It also helps when refilling, sizing a pump or filter, and budgeting for the season. Always confirm dosing against the product's own instructions.