Pool Volume Calculator

A pool volume calculator works out how much water your pool holds — in gallons and litres — from its shape and dimensions. It's the first number you need for everything else: salt, chlorine, shock, stabiliser and algaecide are all dosed per gallon, so getting the volume right keeps your water balanced and your chemicals from being wasted.

Your measurements

Result

Pick rectangle, round or oval, enter the size and the shallow and deep depths, and it averages the depth for you. The result feeds straight into the salt and chlorine calculators.

How it is calculated

Volume = surface area × average depth, converted to gallons (1 cubic foot = 7.48 US gallons). Average depth = (shallow + deep) ÷ 2. Round pools use π·r²·depth; oval pools use π × (length/2) × (width/2) × depth. Irregular pools: split into sections and add them.

Steps

Choose your pool shape.
Enter the length and width (or diameter for a round pool).
Enter the shallow-end and deep-end depths — the tool averages them.
Read the volume in gallons (and litres).
Use that gallon figure in the salt and chlorine calculators for dosing.

Worked example

A 32 × 16 ft rectangular pool that's 3 ft at the shallow end and 8 ft at the deep end averages 5.5 ft deep and holds about 21,000 gallons.

Common questions

How do I calculate my pool's volume?

Multiply the surface area by the average depth, then convert to gallons. The calculator does it for rectangle, round and oval pools.

Why do I need my pool's gallons?

Every pool chemical — salt, chlorine, shock, stabiliser — is dosed by volume. The wrong volume means the wrong dose.

How do I find average depth?

Add the shallow-end and deep-end depths and divide by two. The calculator does this from the two depths you enter.

My pool is an odd shape — what do I do?

Break it into rectangles or circles, calculate each, and add the volumes together for the total.