Pool Volume Calculator
Find out how many gallons or litres of water your swimming pool holds. Pick the shape, enter the size and depths, and get the volume — handy for dosing chemicals and heating.
Quick answer: Pool gallons = length × width × average depth (in feet) × 7.48. A 32 × 16 ft pool averaging 5.5 ft deep holds about 21,000 US gallons.
Knowing your pool's volume is the starting point for dosing chlorine and other chemicals, sizing a heater or pump, and estimating water-refill costs. The volume is the surface area multiplied by the average water depth, then converted to gallons or litres.
How pool volume is calculated
Round: π × (diameter ÷ 2)² × avg depth
Oval: π ÷ 4 × length × width × avg depth
× 7.48 for US gallons (feet), or × 1000 for litres (metres, from cubic metres). Avg depth = (shallow + deep) ÷ 2.
Worked example
A rectangular pool 32 ft long and 16 ft wide, sloping from 3 ft to 8 ft, has an average depth of 5.5 ft. Volume = 32 × 16 × 5.5 = 2,816 cubic feet, and 2,816 × 7.48 = about 21,065 US gallons (roughly 79,700 litres).
Why average depth matters
Most pools have a shallow and a deep end, so a single depth would over- or under-state the volume. Averaging the two gives the correct water volume for a pool with a straight slope. If your pool has a flat bottom, enter the same figure for both depths.