12 free tools
Pool & Hot Tub calculators
Pool volume, chlorine, salt, alkalinity, hardness and stabilizer doses, water balance, heater sizing and running costs for pools and hot tubs. Each tool shows the formula, worked examples and sources.
Pool & Hot TubHot Tub Chemical CalculatorExact chlorine and alkalinity doses for your hot tub or spa in grams and ounces, with CDC-recommended levels for chlorine, bromine and pH.Pool & Hot TubPool Alkalinity CalculatorHow much baking soda raises total alkalinity, or how much muriatic acid or dry acid lowers it, for your pool or hot tub.Pool & Hot TubPool Calcium Hardness CalculatorHow much calcium chloride raises calcium hardness, or how much water to replace to lower it, for your pool or spa.Pool & Hot TubPool Chemical CalculatorEnter your test results once and get every dose: chlorine, alkalinity, calcium hardness, stabilizer and salt, in the right order.Pool & Hot TubPool Chlorine CalculatorHow much liquid chlorine, bleach, cal-hypo, dichlor or trichlor to add to raise free chlorine to your target, in gallons or litres.Pool & Hot TubPool Heater Size CalculatorHow long your heater takes to warm the pool or hot tub, and what size gas heater or heat pump you need to heat it in a given time.Pool & Hot TubPool Heating Cost CalculatorCost to heat your pool or hot tub with natural gas, propane, a heat pump or an electric heater, per heat-up and per month.Pool & Hot TubPool Pump Cost CalculatorWhat your pool pump costs to run per day, month and year, for single-speed or variable-speed pumps, and how much switching saves.Pool & Hot TubPool Salt CalculatorHow much salt to add to a saltwater pool to reach your chlorinator's target ppm, in pounds or kilograms and bags.Pool & Hot TubPool Stabilizer CalculatorHow much cyanuric acid (stabilizer, conditioner) to add to an outdoor pool, or how much water to replace when it is too high.Pool & Hot TubPool Volume CalculatorHow many gallons or litres your pool or hot tub holds: rectangle, round, oval, kidney or sloped floor, in feet or metres.Pool & Hot TubPool Water Balance Calculator (LSI)Langelier Saturation Index for pools and hot tubs: see whether your water will etch plaster, corrode metal or form scale.