Pool Volume & Dosing Calculator
Calculate your swimming pool's volume from its shape and depth, then get the chlorine, stabilizer, alkalinity and salt doses it needs.
Flat-bottomed pool? Put the same depth in both boxes. Measure water depth, not wall height.
Enter your pool dimensions — the volume and chemical doses update as you type.
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- US gallons
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- Liters
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- Cubic meters
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- Cubic feet
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- Average depth
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- Surface area
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- Pump flow for 8 h turnover
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- Formula used
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Chemical dosing
Pick how much you want each reading to rise; the dose is worked out for the volume above. Add chemicals gradually, retest after a full turnover, and follow the label on the product.
| Goal | Raise by (ppm) | Product | Dose |
|---|---|---|---|
| Free chlorine | Liquid chlorine (12.5% sodium hypochlorite) | — | |
| Cal-hypo granules (73% available chlorine) | — | ||
| Dichlor granules (56% available chlorine) | — | ||
| Stabilizer (CYA) | Cyanuric acid (100%) | — | |
| Total alkalinity | Baking soda (sodium bicarbonate) | — | |
| Salt (SWG pools) | Pool salt (sodium chloride) | — |
Doses assume fresh, full-strength product and a pool that is already circulating. Real pools lose chlorine to sun and swimmers, and granular products vary in purity — treat these numbers as a starting point, test the water afterwards, and never mix chemicals together in a bucket.
How it works
Volume comes from the classic pool-industry formulas: a rectangle is
length × width × average depth, a round pool is π × radius² × average depth,
an oval is π × (length ÷ 2) × (width ÷ 2) × average depth, and a kidney or freeform
pool uses the standard approximation 0.45 × (width A + width B) × length × average depth.
Average depth is taken as the mean of the shallow and deep ends, which is exact for a
constant-slope floor. Cubic feet are converted with 1 ft³ = 7.480519 US gallons = 28.3168 liters.
The dosing table works in milligrams per liter (1 ppm = 1 mg/L). Liquid chlorine is treated as 12.5% available chlorine by weight/volume (125 g per liter), cal-hypo as 73% and dichlor as 56%, so one ppm of free chlorine needs volume × 1 mg/L ÷ the product's strength. Cyanuric acid and salt are dosed one-to-one with the water volume, and baking soda is dosed stoichiometrically — 84.007 g of sodium bicarbonate delivers 50.04 g of alkalinity as calcium carbonate, which is why roughly 1.4 lb per 10,000 gallons lifts total alkalinity by 10 ppm.
Everything is arithmetic done in your browser with plain JavaScript. Nothing about your pool is uploaded, stored or sent anywhere — no sign-up, no ads, and the page keeps working offline.
Frequently asked questions
How do I work out how many gallons my pool holds?
Multiply the surface area by the average depth to get cubic feet, then multiply by 7.480519 to get US gallons. For a rectangle that is length × width × average depth; a round pool is π × radius² × average depth; an oval is π × (length ÷ 2) × (width ÷ 2) × average depth; a kidney or freeform pool uses the standard 0.45 × (width A + width B) × length × average depth approximation. Average depth is the mean of the shallow and deep ends, which is exact when the floor slopes evenly.
How much chlorine does my pool need for 1 ppm?
One ppm is one milligram per liter, so a 20,000 gallon (75,700 litre) pool needs about 76 grams of actual chlorine per ppm. That is roughly 605 ml of 12.5% liquid chlorine, about 104 grams of 73% cal-hypo granules, or about 135 grams of 56% dichlor. The calculator does this maths for your exact volume — enter the ppm rise you want and read off the dose for whichever product you use.
How much baking soda raises pool alkalinity by 10 ppm?
About 1.4 lb (roughly 640 grams) per 10,000 gallons. Sodium bicarbonate weighs 84.007 g per mole and delivers 50.04 g of alkalinity measured as calcium carbonate, so every 1 ppm of total alkalinity needs 1.68 mg of baking soda per litre of water. Add it in stages over a day, brush it around, and retest after a full turnover.
Is this pool calculator private and free?
Yes. Every calculation runs in your browser with plain JavaScript — your pool dimensions are never uploaded, stored or sent anywhere. There is no sign-up, no account and no ads, and the page keeps working if you lose your connection at the poolside.