Pentair Pool Volume Calculator
Pentair pool volume calculator works out Volume and Water surface area from Pool shape, Length and Width. The default figures on this page give product to add of 422.759 lb; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
5 steps
- Average depth = (3 + 8) / 2 = 5.5 ft
- Volume = 32 x 16 x 5.5 = 2816 cu ft
- US gallons = 2816 cu ft x 1728/231 = 21065.142857142855 gal (231 cu in per gallon, exact)
- Salt = 21065.142857142855 gal x 2400 ppm x 8.34540445 lb/gal / 10^6 = 421.91312865572564 lb of NaCl
- At 99.8% purity that is 422.7586459476209 lb of product
Figures from pool chemical dosing constants, 2021 edition, checked 31 August 2026. Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed · how reference data is kept current
Sources and references
3 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the pentair pool volume calculator calculates
Works out swimming-pool volume in cubic feet, US gallons and litres for rectangular, round and oval pools, then doses salt, chlorine, alkalinity increaser, calcium hardness increaser or stabiliser to move the water from its measured level to a target.
How to use this pentair pool volume calculator
Enter Pool shape, Length, Width and Diameter. Volume updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Volume, Water surface area and Average depth used.
The method follows NIST Special Publication 811 / NIST Handbook 44 (US gallon = 231 cubic inches exactly, so 1 cu ft = 1728/231 US gal), CDC Model Aquatic Health Code, 4th edition (2023): operating envelope for pH, free available chlorine and cyanuric acid, and the requirement to apply chemicals per the registered label and ANSI/APSP/ICC-11, American National Standard for Water Quality in Public Pools and Spas (industry ideal ranges quoted in warnings).
What you can compare
Change one input at a time to see how it affects Volume, Water surface area and Average depth used. The inputs you can vary are Pool shape, Length, Width, Diameter, Average depth and Shallow end depth.
Understanding Volume, Water surface area and Average depth used
Pool chemistry is a safety matter. Doses are computed from your measured water test and the product label strength you selected; always follow the EPA-registered label on the product you actually hold, never mix chemicals, add chemical to water rather than water to chemical, and retest before adding more. This engine does not decide whether a pool is safe to swim in.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I calculate my pool volume?
Works out swimming-pool volume in cubic feet, US gallons and litres for rectangular, round and oval pools, then doses salt, chlorine, alkalinity increaser. Open “How this is worked out” beside the result to see each step for your own figures.
How many gallons is a 40x20 pool?
On the figures this page opens with — length 10 ft, width 20 ft and average depth 5 ft — the product to add is 422.759 lb. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What is the volume of a 16x32 pool?
It needs Pool shape, Length, Width, Diameter, Average depth and Shallow end depth. Nothing else is required, and the figures stay in your browser.
What information do I need for the pentair pool volume calculator?
You need Pool shape, Length, Width, Diameter, Average depth, Shallow end depth, Deep end depth and Known volume. The page opens with default figures that give product to add of 422.759 lb, so you can see the scale before entering your own.
What does this pentair pool volume calculator show?
It shows Volume, Water surface area, Average depth used, Product to add, Product to add (liquids), Chemical and Cyanuric acid this dose also adds, with the working and any warnings for your entries.
Can I check how the pentair pool volume calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.