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About This Calculator
Knowing your pool's exact water volume is critical for proper chemical dosing, heater sizing, pump selection, and calculating fill costs. Underdosing chemicals leads to algae and bacteria, while overdosing causes skin irritation and equipment corrosion. This calculator handles rectangular, circular, oval, and irregular pool shapes with varying depths to give you a precise gallon or liter count.
Quick Tips
- 1 Rectangular pool volume: length x width x average depth x 7.48 gallons/cu ft.
- 2 Round pools use pi x radius^2 x depth; multiply by 7.48 for gallons.
- 3 Kidney-shaped pools need 0.45 x (A+B) x length x depth for volume.
Example Calculation
Rectangular pool 30ft x 15ft, shallow 3.5ft to deep 8ft.
Average depth: 5.75 ft | Volume: 2,587.5 ft3 | Water: 19,354 gallons | Fill at 10 GPM: ~32 hours
How to Calculate Pool Volume
Pool volume depends on shape and average depth. For rectangular pools: Length x Width x Average Depth x 7.48 gallons per cubic foot. For circular pools: pi x radius squared x Average Depth x 7.48. Average depth is calculated as (shallow depth + deep depth) / 2 for pools with a gradual slope.
Why Pool Volume Matters
Knowing your pool volume is essential for proper chemical treatment, including chlorine, pH balancers, algaecide, and shock treatments. Incorrect dosing can lead to unsafe water or wasted chemicals. Volume is also needed for calculating pump sizing, heater BTU requirements, and water replacement costs.
Frequently Asked Questions
A typical residential pool holds 10,000 to 30,000 gallons. A small above-ground pool (15 feet round, 4 feet deep) holds about 5,300 gallons. A large in-ground pool (20x40 feet, 5 feet average depth) holds about 30,000 gallons.
One cubic foot of water equals 7.48 US gallons. This conversion factor is used to convert the pool volume from cubic feet to gallons, which is the standard unit for pool chemical dosing.
For a pool with a uniform slope, average depth = (shallow end + deep end) / 2. For pools with a hopper bottom or irregular shape, measure depth at several points and average them for a more accurate estimate.