Pool Size and Water Calculators
Volume is the number every dose depends on. Start here, then work out fill time, normal water loss and partial drains.
- Pool Volume CalculatorWork out how many gallons or litres your pool holds. Works for rectangle, round, oval and kidney pools with a shallow and deep end, and shows the maths.
- Pool Fill Time and Cost CalculatorHow long will your pool take to fill with a garden hose, and what will the water cost? Time a bucket, enter your water rate and get hours and dollars.
- Pool Evaporation CalculatorEstimate how much water your pool loses to evaporation each day and week from temperature, humidity and wind, and check whether the drop points to a leak.
- Pool Drain and Refill CalculatorFind how much water to drain and refill to lower stabilizer (CYA), salt, calcium or TDS, allowing for your fill water and for partial drains.
Where to start
Volume comes first. Every chemical dose is a concentration multiplied by the amount of water, so a volume that is 20% off makes every dose 20% off. Measure at the water line, use the pool volume calculator, and the site will remember the answer for the other calculators.
Water in, water out
Pools gain water from the hose and from rain, and lose it to evaporation, splash-out, backwashing and leaks. Evaporation is normal and depends on the weather: warm water, dry air and wind all speed it up. The EPA treats a drop of more than about 2 inches a week as a sign worth checking for leaks. The evaporation calculator tells you what’s normal for your conditions.
Some things only leave the pool with the water. Stabilizer (CYA), salt, calcium and dissolved solids build up over time, and the only reliable way to bring them down is to drain some water and refill. The drain and refill calculator works out how much, including when your fill water already contains some of what you’re trying to remove.