Hot tub chemistry calculators
9 free hot tub calculators: chlorine, bromine, MPS shock, pH and alkalinity, volume, drain interval and safe-to-soak. Every calculator uses the same chemistry engine as the Spa Calc app.
- All-in-one hot tub calculatorEnter a test. Get every dose in order, and whether you can soak.
- Hot tub chlorine calculatorDichlor or bleach, in teaspoons and grams, for your tub.
- Hot tub bromine calculatorBromide reserve for new water, and how to raise bromine.
- Drain interval calculatorDays between drains from your volume and soakers.
- Hot tub volume calculatorGallons or litres for inflatable, round and square tubs.
- Hot tub pH and alkalinity calculatorpH down, pH up or alkalinity up, sized for your tub.
- Ready to soak?Soak, wait or fix first, from your test and your last dose.
- MPS shock calculatorNon-chlorine shock after soaks or weekly.
- Bromine to chlorine converterChlorine reading to bromine, and back (× 2.25).
Looking for a quick number for a common size? See Doses by tub size.