Pool & spa calculators
6 free tools
The everyday pool-owner questions, sorted out with simple math. Start by finding how many gallons your pool holds — nearly every other calculation depends on it — then dose chlorine and salt, drop your pH with acid, price out a heat-up, and figure out how long to run the pump.
Estimate the muriatic acid needed to lower your pool's pH to a target level.
Find how much liquid or granular chlorine to add to raise free chlorine by a target ppm.
Estimate the energy and cost to raise your pool's temperature by a chosen number of degrees.
Work out how long to run your pump to turn over the water, plus the daily energy cost.
Work out how many pounds of salt to add to reach your target salinity from your current level.
Work out how many gallons and liters your pool holds from its shape and dimensions.
Frequently asked questions
Why does pool volume matter so much?
Almost every chemical dose is figured per 10,000 gallons, so if your gallon count is off, every dose is off too. Measure your pool once and reuse that number for chlorine, salt, and acid.
Are these dosing amounts exact?
They're solid starting points built on standard industry rates, but water chemistry varies with temperature, alkalinity, and stabilizer. Add in stages, wait, and retest before topping up — it's far easier to add more than to undo an overdose.
How often should I test the water?
Test free chlorine and pH a couple of times a week in swim season, and check salt and alkalinity every week or two. Always retest a few hours after adding chemicals so the reading reflects fully mixed water.