Pool Volume Calculator
Knowing the volume of your swimming pool is essential for correct chemical treatment, accurate water cost estimates, and sizing pumps and filters. Pool chemical dosages are always specified per 1,000 gallons or per 10,000 gallons, so an inaccurate volume estimate can lead to underdosing (unsafe water) or overdosing (wasted chemicals and potential irritation). This calculator supports four common pool shapes: rectangular, round, oval, and kidney (an approximation using the standard industry formula 0.45 x (A+B) x Length x Depth, where A and B are the two widths at the widest and narrowest points). For pools with a shallow end and a deep end, enter the average depth: add the shallow and deep depths together and divide by 2. The conversion to gallons uses 7.481 gallons per cubic foot, and to liters uses 28.317 liters per cubic foot. For above-ground oval pools, the oval formula applies. Always account for water lost to splashing and evaporation when refilling; pool chemistry should be retested after significant water addition.
Pool volume formulas
Rectangular: Volume = Length x Width x Depth
Round: Volume = pi x (Diameter/2)^2 x Depth
Oval: Volume = pi/4 x Length x Width x Depth
Kidney: Volume = 0.45 x (Width A + Width B) x Length x Depth
Gallons = Cubic feet x 7.481
Liters = Cubic feet x 28.317
Worked example (rectangular)
Pool: 30 ft x 15 ft, average depth 5 ft.
- Cubic feet = 30 x 15 x 5 = 2,250.00 cu ft
- Gallons = 2,250 x 7.481 = 16,832.25 gal
- Liters = 2,250 x 28.317 = 63,713.25 L
Frequently asked questions
How many gallons of water does a typical swimming pool hold?
A standard residential rectangular pool (15 ft x 30 ft, 5 ft average depth) holds about 16,875 gallons. An 18-ft round above-ground pool with 4 ft depth holds about 7,646 gallons. The exact volume depends on the pool's shape and dimensions.
Why do I need to know my pool volume?
Knowing your pool volume is essential for correct chemical dosing. Pool chemicals such as chlorine, algaecide, shock, and pH adjusters are all dosed by volume. An incorrectly dosed pool can be unsafe for swimming or ineffective at controlling algae and bacteria.
How do you calculate the volume of a kidney-shaped pool?
A kidney-shaped pool is approximated using the formula: Volume = 0.45 x (Width at widest + Width at narrowest) x Length x Average depth. This is an industry-standard approximation for irregular kidney shapes.
How is average pool depth calculated?
For pools with a shallow end and a deep end, average depth = (Shallow depth + Deep depth) / 2. For pools with a long shallow section and a short deep section, a weighted average may be more accurate. This calculator uses the simple average.
How many liters are in a gallon?
One US gallon equals approximately 3.785 liters. This calculator shows both gallons and liters so you can match whichever unit your pool chemicals specify.
Sources
- Association of Pool and Spa Professionals (APSP): pool volume calculation methods.
- CDC Healthy Swimming: Pool water treatment guidance.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. Kidney shape is an approximation. Always test pool water chemistry before adding chemicals.