Pool volume calculator

Pool volume is the surface area times the average depth. For a sloping floor, average the shallow and deep ends. An 8 × 4 m pool running from 1.2 m to 2 m holds 51,200 litres, or about 13,500 US gallons.

Volume is the number every chemical dose is calculated from, which is why getting it roughly right matters more than getting it exactly right. Chlorine, acid and algaecide are all dosed per cubic metre or per ten thousand litres, and a pool assumed to be a fifth smaller than it is will be persistently under-treated. The pump figure is the other practical output: domestic filtration is sized to turn the whole volume over in six to eight hours, so a 50,000 litre pool wants roughly 105 litres a minute — and a pump much larger than that pushes water through the filter too fast to clean it.