Find out how many gallons your pool holds. Pick the shape, enter the size and the water depth, and this pool volume calculator gives you US gallons, liters, cubic feet and the weight of the water. This free online pool volume calculator works on any phone or computer, with no sign-up or download.
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Pool water needed
— US gallons
Quick answer: gallons = length × width × average depth (all in feet) × 7.48. For a round pool: diameter² × depth × 5.87.
A US gallon is exactly 231 cubic inches, so one cubic foot (1,728 in³) holds 1,728 ÷ 231 = 7.4805 gallons. Rounding that to 7.5, as many pool guides do, overstates the volume by about 0.3%.
| Shape | Gallons |
|---|---|
| Rectangle, one depth | L × W × D × 7.48 |
| Rectangle, sloped floor (even slope) | L × W × (shallow + deep) ÷ 2 × 7.48 |
| Round | π × (diameter ÷ 2)² × D × 7.48 = diameter² × D × 5.87 |
| Oval | π × (long ÷ 2) × (short ÷ 2) × D × 7.48 = long × short × D × 5.87 |
| Free-form, known area | surface area × average depth × 7.48 |
All measurements are in feet. The 5.87 is π ÷ 4 × 7.4805. The sloped-floor formula averages the two end depths, which is exact only for a floor that slopes evenly from end to end. Pools with a flat shallow area and a steep drop (a “hopper” or “sport” bottom) are approximated by it, so split them into sections for a closer figure.
For a kidney or L-shaped pool, split it into rectangles and circles, add each to the pool total, or use the surface area if you know it.
| Pool | Water depth | US gallons | Liters |
|---|---|---|---|
| 15 ft round | 4 ft | 5,288 | 20,016 |
| 18 ft round | 4 ft | 7,614 | 28,823 |
| 24 ft round | 4 ft | 13,536 | 51,241 |
| 12 × 24 ft rectangle | 5 ft | 10,772 | 40,776 |
| 16 × 32 ft rectangle | 4 ft | 15,320 | 57,993 |
| 16 × 32 ft rectangle | 3.5–8 ft (5.75 average) | 22,023 | 83,365 |
| 20 × 40 ft rectangle | 3.5–8 ft (5.75 average) | 34,410 | 130,257 |
Also: ramp, uneven depth, tapered bed
V = L × W × (h₁ + h₂) ÷ 2
L = length, W = width, h₁ and h₂ = depth at each end.
Example: An in-ground pool 32 × 16 ft whose floor slopes evenly from 8 ft at the deep end to 3.5 ft at the shallow end: 32 × 16 × 5.75 = 2,944 cu ft × 7.48 = 22,023 gallons.
Also: rectangular prism, bed, trench, room
V = L × W × H
L = length, W = width, H = height or depth.
Example: A 24 × 12 ft pool with 5 ft of water throughout: 24 × 12 × 5 = 1,440 cu ft × 7.48 = 10,772 gallons.
Also: round hole, post hole, tank, planter
V = π × r² × h
r = radius (half the diameter), h = height.
Example: A round above-ground pool 24 ft across with 4 ft of water: π × 12² × 4 = 1,810 cu ft × 7.48 = 13,536 gallons.
Also: elliptical cylinder, stock tank, oval pool
V = π × a × b × h
a = half the long width, b = half the short width, h = height.
Example: An oval pool 30 × 15 ft with 4 ft of water: π × 15 × 7.5 × 4 = 1,414 cu ft × 7.48 = 10,575 gallons.
Also: square feet to cubic feet
V = A × d
A = area, d = depth or thickness.
Example: A free-form pool with a surface area of 450 sq ft and an average depth of 5.5 ft: 2,475 cu ft × 7.48 = 18,514 gallons.
Work out the volume in cubic feet (length × width × average depth for a rectangle) and multiply by 7.48, the number of US gallons in a cubic foot. A 24 × 12 ft pool with 5 ft of water holds 1,440 cu ft, or 10,772 gallons.
For a pool that slopes evenly, add the shallow-end and deep-end water depths and divide by 2: (3.5 + 8) ÷ 2 = 5.75 ft. If the floor has a steep drop into a deep area, split the pool into a shallow section and a deep section and add both to the pool total.
To the water line. Pools are filled to the middle of the skimmer opening, a few inches below the top, so measure the depth of the water itself.
At 4 ft of water, π × 12² × 4 = 1,810 cu ft, which is about 13,536 gallons. At 4.5 ft it is about 15,228 gallons. Enter your own water depth for an exact figure.
Chemical doses, pump and filter sizing, heater sizing and the cost of filling all depend on it. Product labels state doses per 10,000 gallons, so getting the gallons right matters.
Fresh water weighs about 62.4 lb per cubic foot, or about 8.34 lb per US gallon. A 10,000 gallon pool holds about 83,400 lb, or nearly 42 tons, of water.
One cubic foot is 28.32 liters, and one US gallon is 3.785 liters. In metric countries the calculator shows liters and cubic meters first.
Yes. The CalcWall Pool Volume Calculator is completely free and works online in any browser, on a phone, tablet or computer. There is nothing to download and no account to create, and the math runs right in your browser, so results appear as you type.