How it’s calculated
- Average depth = (shallow + deep) ÷ 2
- Rectangle: L × W; round: π ÷ 4 × D²; oval: π ÷ 4 × L × W
- Gallons = area × average depth × 7.48
- Fill time = gallons ÷ gpm ÷ 60
Worked example
32 × 16 ft rectangular pool, 3.5 ft to 6 ft deep, filled at 8 gpm.
Inputs
- Pool shape
- Rectangular
- Length (diameter for round)
- 32 ft
- Width (ignored for round)
- 16 ft
- Shallow end depth
- 3.5 ft
- Deep end depth
- 6 ft
- Fill flow rate
- 8 gpm
- Water price per 1,000 gallons
- 0 $/1,000 gal
Results
- Pool volume
- 18,193 gal
- Fill time
- 37.9 hours
Assumptions and limits
- Uniform slope between shallow and deep ends. Hopper-bottom pools hold less.
- Oval treated as an ellipse; oval pools with straight sides hold slightly more.
Verify the result against the applicable local code, adopted code edition, manufacturer instructions and project requirements. See our methodology.
Questions
How many gallons is a 16×32 pool?
At an average 4.75 ft deep, about 18,200 gallons.
How long does it take to fill a pool with a hose?
At 8 gpm, 18,000 gallons takes about 38 hours. Water delivery trucks are faster for large pools.