Pool and hot tub chemistry, worked out for you
Enter your volume and test results, pick the product on your shelf, and get the dose with the math shown. No sign-up, nothing to install.
Calculators
CalculatorAlkalinity, calcium and stabilizerBaking soda, muriatic acid, calcium chloride and stabilizer amounts.CalculatorChlorine dose calculatorLiquid chlorine, bleach, cal-hypo, dichlor or trichlor, with side effects.CalculatorPool volume calculatorGallons from length, width and depth for rectangle, round and oval pools.CalculatorPool water logRecord readings on your device, spot trends, export a CSV.
New to pool care? Do it in this order
- Find your true volumeEvery dose depends on it. Measure once and save the number.
- Test properlyKnow what each test measures and which ones you can trust.
- Fix things in the right orderAlkalinity and pH before calcium, stabilizer before chlorine targets.
- Dose chlorinePick your product strength and target.
- Log your resultsA few weeks of numbers shows your pool's chlorine use.
Guides
GuideFree chlorine and CYAWhy higher stabilizer means you need more chlorine.GuideHot tub water careCDC levels, chlorine versus bromine, and a weekly routine.GuideHow to test pool waterWhich tests to trust and how to take a good sample.GuidePool chemical safetyStorage, never-mix rules, gear and spills.GuideWhat to adjust firstThe sequence that stops one fix from undoing another.
How this site works
Math shown
Every calculator explains its formula and gives a worked example you can check by hand.
Sources dated
Guidance from the CDC and other sources is linked and dated on each page.
Private
Calculators run in your browser. Logs stay on your device.
New to the terms? Our glossary explains them in plain words.