How to calculate pool volume
Volume is the surface area times the average depth, converted to gallons:
Gallons = Surface area (ft²) × average depth (ft) × 7.48
Surface area depends on the shape: length × width for rectangular, π × radius² for round, and π × (length ÷ 2) × (width ÷ 2) for oval. A 32 × 16 ft rectangular pool averaging 5 ft deep holds about 19,150 gallons.
Finding your average depth
If your pool has a shallow and a deep end, average them: a pool 3 ft at one end and 7 ft at the other averages 5 ft. For a constant-depth pool, just use that depth.
Why volume matters
- Chemicals: chlorine, shock, and balancers are dosed per gallon.
- Equipment: pumps and filters are sized to turn over the volume.
- Filling & heating: both scale directly with gallons.
Frequently asked questions
How do I calculate the volume of my pool?
Find the surface area, multiply by the average depth (all in feet) for cubic feet, then multiply by 7.48 to get gallons. A 32 ft × 16 ft rectangular pool with a 5-foot average depth is 32 × 16 × 5 = 2,560 cubic feet, or about 19,150 gallons.
What is the average depth if my pool has a deep end?
For a pool that slopes from shallow to deep, the average depth is roughly (shallow depth + deep depth) ÷ 2. A pool that is 3 feet at one end and 7 at the other averages 5 feet. Enter that average for an accurate volume.
Why do I need to know my pool's volume?
Volume drives almost everything in pool care: how much chlorine, shock, algaecide, or other chemicals to add, how to size a pump and filter, and how long it takes to fill or heat. Dosing instructions are almost always given per number of gallons.
How many gallons are in a cubic foot?
About 7.48 US gallons per cubic foot. So once you have the volume in cubic feet, multiply by 7.48 for gallons. To convert gallons to liters, multiply by 3.785.
Disclaimer: This estimates volume from a single average depth and a regular shape. Irregular or free-form pools will differ — for precise chemical dosing, round conservatively and retest the water.