Pool & Spa Tools

Free swimming-pool and hot-tub calculators that run entirely in your browser — pool volume, chlorine and shock dosing, pH, alkalinity, calcium hardness and cyanuric-acid adjustment, salt dosing, the Langelier saturation index, heating time and drain time. Get your water balanced without uploading anything.

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Pool Volume Calculator

Find your swimming pool's water volume in gallons and liters from its shape and depths, with average-depth handling for sloped floors.

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Chlorine Dose Calculator

Find how much chlorine or bleach to add to raise your pool's free chlorine to a target ppm, for liquid, cal-hypo, dichlor, trichlor, or lithium.

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Pool Shock (Breakpoint) Calculator

Find the breakpoint-chlorination shock dose to clear chloramines using the 10× combined-chlorine rule, for any chlorine product and pool size.

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Pool pH Adjuster

Find how much muriatic acid to lower pH or soda ash to raise it toward your target, scaled to pool volume and total alkalinity.

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Total Alkalinity Increaser Calculator

Find how much baking soda (sodium bicarbonate) to add to raise your pool's total alkalinity to a target ppm, with a safe single-dose cap.

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Calcium Hardness Increaser Calculator

Find how much calcium chloride to add to raise your pool's calcium hardness to a target ppm, for anhydrous or dihydrate flake at any purity.

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Cyanuric Acid (Stabilizer) Calculator

Work out how much cyanuric acid (chlorine stabilizer) to add to reach a target CYA level, or how much water to drain to lower it.

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Saltwater Pool Salt Calculator

Find how many pounds or bags of pool salt to add to reach your target salinity for a salt-chlorine generator, or how much to drain to lower it.

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LSI Water Balance Calculator (Langelier)

Compute the Langelier Saturation Index from pH, temperature, calcium hardness, alkalinity, CYA, and TDS to see if pool water is corrosive, balanced, or scaling.

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Pool Heating Time & Cost Calculator

Estimate the energy, run time, and cost to raise your pool temperature with a gas heater or heat pump, from volume, temperature rise, and energy price.

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Pool Drain & Dilution Calculator

Calculate how much water to drain and refill to lower a chemical that only dilution can reduce — cyanuric acid, salt, calcium hardness, or TDS.

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