Pool Volume Calculator
Calculate swimming pool volume in gallons and liters for rectangular, circular, oval, and kidney-shaped pools. See also Tank Volume Calculator, Pipe Volume Calculator, and Cubic Yard Calculator.
Pool Shape
How to Use the Pool Volume Calculator
Select your pool shape and enter the dimensions. For pools with varying depth, enter the shallow end and deep end depths — the calculator uses the average depth. For kidney or freeform pools, measure the longest length and widest width; the calculator applies a 0.75 multiplier to approximate the irregular shape. Enter a flow rate in GPM to estimate fill time. The chlorine dosage shown is for initial treatment at standard concentration.
Formula
Average Depth = (Shallow + Deep) / 2
Rectangular: V = L x W x Avg Depth x 7.48 gal/ft³
Circular: V = PI x r² x Avg Depth x 7.48
Oval: V = PI x (L/2) x (W/2) x Avg Depth x 7.48
Kidney: V = L x W x Avg Depth x 0.75 x 7.48
Example Calculation
Rectangular pool: 30 ft x 15 ft, 3 ft shallow, 8 ft deep
Average depth = (3 + 8) / 2 = 5.5 ft
Volume = 30 x 15 x 5.5 = 2,475 cu ft
Gallons = 2,475 x 7.48 = 18,513 gallons
Fill time at 10 GPM = 18,513 / 600 = 30.9 hours
Common Pool Sizes Reference
| Pool Size | Avg Depth | Gallons | Type |
|---|---|---|---|
| 12 x 24 ft | 5 ft | 10,800 | Small residential |
| 16 x 32 ft | 5.5 ft | 21,100 | Medium residential |
| 20 x 40 ft | 5.5 ft | 33,000 | Large residential |
| 18 ft round | 4 ft | 7,600 | Above-ground |
| 24 ft round | 4 ft | 13,500 | Above-ground (large) |
| 25 x 50 m | 2 m | 660,000 | Olympic competition |
Frequently Asked Questions
How many gallons is a typical residential pool?
Most residential in-ground pools hold 10,000-30,000 gallons. A common 16x32 ft pool with 5.5 ft average depth holds about 21,000 gallons. Above-ground pools typically hold 5,000-15,000 gallons depending on size.
How long does it take to fill a pool with a garden hose?
A standard garden hose delivers 5-10 GPM. A 20,000-gallon pool takes 33-67 hours (1.5-3 days) to fill with one hose. Using two hoses or a fire hydrant fill service (500+ GPM) significantly reduces fill time.
How much chlorine does my pool need?
Maintain 1-3 ppm free chlorine. For initial treatment, add about 6 oz of liquid chlorine (12.5% sodium hypochlorite) per 10,000 gallons to raise levels by 1 ppm. Shock treatment requires 1 lb of calcium hypochlorite per 10,000 gallons.
How do I measure an irregularly shaped pool?
For kidney or freeform pools, measure the longest length and widest width, then multiply by 0.75 (the shape factor). For L-shaped pools, divide into rectangles and calculate each section separately, then add the volumes together.
How much does it cost to fill a pool with water?
At average US water rates ($4-8 per 1,000 gallons), filling a 20,000-gallon pool costs $80-160. Some areas charge higher rates for large volumes. Water delivery by truck costs $200-600 for a full pool but is faster.
How much water does a pool lose to evaporation?
Pools lose 1/4 to 1/2 inch of water per day to evaporation in summer (more in hot, dry, windy climates). A 16x32 ft pool losing 1/4 inch daily loses about 80 gallons per day, or 2,400 gallons per month. Pool covers reduce evaporation by 90-95%.