It is essential to know how much water a pool holds. Though dose rates of pool chemicals do not have to be accurate down to the last gram or millilitre, they must be realistically close to the recommended levels.

It is not uncommon for pool owners to underestimate the amount of water in a pool, continuously under-dose, and then wonder why they have trouble.
Calculating pool volume is simply done, using the following equations.

Rectangular or square pools

rectMultiply length (metres) x width (metres) x average depth (metres) x 1000 = litres.

Circular pools

circularMultiply the diameter (metres) x diameter (metres) x depth (metres) x 0.79 x 1000 = litres.

Oval pools

ovalMultiply the long diameter (metres) x short diameter (metres) x average depth (metres) x 0.79 x 1000 = litres.

Kidney-shaped or other irregularly shapes pools

kidneyUnusual pools can often be broken down into basic shapes for purposes of calculation. For example, a kidney shaped pool is roughly two circles joined together. Calculate the volume of the circles and add on about 10% to cover the area not included in the calculation. It is better to overestimate a pool volume than underestimate it

Note : Average depth is calculated by measuring depth at the deep end and at the shallow end, adding the figures together and dividing by two.

A guide to common pool volumes

Circular Pools (metres)
Diam x Diam x Av. Depth x 0.79 x 1000
3.6 x 3.6 x 0.9 x 0.79 9 200
4.5 x 4.5 x 1.2 x 0.79 19 200
6.0 x 6.0 x 1.2 x 0.79 34 200
7.5 x 7.5 x 1.2 x 0.79 53 300
9.0 x 9.0 x 1.2 x 0.79 76 800
Rectangular Pools (metres)
Length x width, x Av. Depth x 1000
7.2 x 3.6 x 1.2 31 100
9.0 x 4.5 x 1.2 48 600
9.0 x 4.5 x 1.5 60 800
10.0 x 5.0 x 1.5 75 000
9.5 x 4.75 x 1.8 81 200

Dimensions (litres)*
Rounded figures*