🏊 Pool Volume Calculator
How many gallons is your pool? Rectangle, round, oval or kidney, flat or sloped floor, in feet or meters — plus liters, fill time and water cost.
Measure the water depth, not the wall height — water usually sits several inches below the top of an above-ground pool wall.
| Surface area | 512.0 sq ft |
|---|---|
| Average depth | 5.75 ft |
| Water weight | ≈ 183,669 lb (83.2 metric tons) |
| US gallons per inch of depth | 319 |
Time to fill: 45 h 53 min
Time a bucket of known size at your hose to find its real flow: gallons ÷ seconds × 60 = gallons per minute.
What Pool Volume Calculator Does
This pool volume calculator tells you how many gallons — and liters — your pool holds. Pick the shape: rectangle, round, oval, kidney, or any pool whose surface area you already know. Enter the dimensions in feet or meters and give the water depth, or the shallow-end and deep-end depths for a pool with a sloped floor.
Knowing the volume is the starting point for water care: chemical labels give doses per volume of water, and pumps, filters and heaters are sized by gallons. The calculator also shows the water’s weight, the gallons in each inch of depth (useful when topping up or draining), how long your hose will take to fill the pool, and what the water will cost.
How to Use Pool Volume Calculator
- Pick the pool shape and feet or meters
- Enter the length and width, or the diameter
- Enter the water depth, or the shallow and deep ends for a sloped floor
- Read the volume in gallons, liters and cubic units
- Add your hose flow and water price for fill time and cost
Formula Used by Pool Volume Calculator
Volume by shape
Rectangle: L × W × D · Round: π × (diameter ÷ 2)² × D · Oval: π × (L ÷ 2) × (W ÷ 2) × D · Kidney ≈ 0.45 × (A + B) × L × D
- D
- Average water depth
- A, B
- Widths across the two rounded ends of a kidney pool
- 7.48
- US gallons in one cubic foot
Worked example
A 32 × 16 ft rectangular pool, 3.5 ft at the shallow end and 8 ft at the deep end.
- Average depth = (3.5 + 8) ÷ 2 = 5.75 ft
- 32 × 16 × 5.75 = 2,944 ft³
- 2,944 × 7.48 = 22,023 gallons
Result: About 22,000 gallons, or 83,400 liters.
Round Pools With 4 ft of Water
| Diameter | US gallons |
|---|---|
| 12 ft | 3,384 |
| 15 ft | 5,288 |
| 18 ft | 7,614 |
| 21 ft | 10,364 |
| 24 ft | 13,536 |
| 27 ft | 17,132 |
| 30 ft | 21,151 |
Handy Conversions
| From | To | Multiply by |
|---|---|---|
| Cubic feet | US gallons | 7.48 |
| US gallons | Liters | 3.785 |
| Cubic meters | Liters | 1,000 |
| Cubic meters | US gallons | 264.2 |
| Liters | Imperial gallons | 0.22 |
| US gallons of water | Pounds | ≈ 8.34 |
How to Read Your Result
Measuring accurately
Measure inside the walls at the waterline, not across the outside of the frame or coping. For depth, measure from the water surface to the floor at both ends. For a free-form pool, the “Other” option lets you enter a surface area taken from the pool’s plans or a measured sketch.
Using gallons per inch
The per-inch figure tells you how much water a change in level represents. On a 32 × 16 ft pool, one inch is about 319 gallons, so losing a quarter inch a day is roughly 80 gallons — compare with a bucket test to tell ordinary evaporation from a leak.
Filling costs
Water bills are usually charged per 1,000 gallons or per hundred cubic feet (748 gallons). Sewer charges are often based on water use too, so ask your utility whether it offers a credit or a separate meter for filling a pool.
Limitations & Accuracy Notes
- Kidney and free-form shapes are approximations; steps, benches and a steep deep-end hopper reduce the real volume.
- Results are in US gallons; multiply liters by 0.22 for imperial gallons.
- The calculator does not recommend chemical doses — follow each product’s label using the volume shown.