Pool Volume Calculator
How many gallons is your pool? Enter the shape and size of the pool and the water depth at the shallow and deep ends. The calculator gives the volume in gallons and liters, and in cubic feet and cubic meters.
Add a section for each part of the pool, or subtract steps and benches.
Use this volume in the Pool Salt Calculator or the Pool Shock Calculator.
- Choose US or Metric. You can still change the unit of any single field, for example inches for the depth of an above-ground pool.
- Pick the shape of the pool and enter its length and width. For a Kidney pool, enter the overall length, and for Width A and Width B, measure straight across the widest point of each of the two rounded ends. For an oval pool with straight sides, add a Rectangle (the overall length minus the width, by the width) and a Circle with a diameter equal to the width as two sections. For a shape that is not listed, choose Known area and enter the surface area.
- Enter the water depth at the shallow end and at the deep end. Measure from the floor of the pool to the water surface, not to the top of the wall. If the bottom is flat, choose One depth, or enter the same value in both fields.
- Use Add section for each extra part of the pool, such as a deep diving area or a tanning ledge. Set a section to Subtract for steps or benches that take up space inside the pool.
Dimension and depth fields accept these formats:
-
Whole numbers and decimals, such as
12or10.5 -
Fractions, such as
3/4 -
Mixed numbers, such as
6 1/2
Choose ft + in as the unit to enter a length such as 3 ft 10 in in two fields. Quantity takes a whole number.
Pool volume formula
The volume of water in a pool is:
Volume = surface area × average depth
The average depth is (shallow end depth + deep end depth) ÷ 2. This assumes the floor slopes evenly from one end to the other. With dimensions in feet, the volume is in cubic feet, and you multiply by 1,728 ÷ 231 ≈ 7.48052 to get US gallons. With dimensions in meters, the volume is in cubic meters, and you multiply by 1,000 to get liters.
- 1 US gallon = 231 in³ = 3.785411784 L
- 1 ft³ ≈ 7.48052 gal, and 1 m³ = 1,000 L ≈ 264.17 gal
- 1 ft = 12 in = 0.3048 m
Many pool guides multiply cubic feet by a rounded 7.5 gallons. The calculator uses the exact value, so its result is about 0.26% lower than a result found with 7.5.
The surface area of each shape is calculated as follows.
| Shape | Area |
|---|---|
| Rectangle | length × width |
| Circle | π × diameter² ÷ 4 (or π × radius²) |
| Oval | π × length × width ÷ 4 |
| Kidney | (width A + width B) × length × 0.45 |
| Known area | the area you enter |
The oval is a true ellipse, with the length and width measured across its longest and widest points. The kidney formula is a pool industry estimate for a shape with two rounded ends of different widths, so treat a kidney pool's volume as an approximation. Measure width A and width B straight across the widest point of each rounded end.
With several sections, the calculator adds the volumes of the sections set to Add and subtracts those set to Subtract. It doesn't add any extra for waste, because the result is the amount of water the pool holds.
Examples
A rectangular pool
A pool 40 ft × 20 ft, 3 ft deep at the shallow end and 8 ft at the deep end, has an average depth of 5.5 ft. Its volume is 40 × 20 × 5.5 = 4,400 ft³, or 32,914 gal (124,594 L). Multiplying by 7.5 instead gives 33,000 gal.
A kidney pool
A kidney pool 32 ft long, with widths of 17 ft and 14 ft, 3 ft to 6 ft deep: (17 + 14) × 32 × 0.45 = 446.4 ft², and 446.4 × 4.5 = 2,008.8 ft³, or about 15,027 gal.
A pool with a deep diving area
A pool 32 ft × 16 ft has a shallow part 20 ft long that goes from 3.5 ft to 5 ft, and a diving area 12 ft long that goes from 5 ft to 8 ft. As two sections, it holds 1,360 + 1,248 = 2,608 ft³, or 19,509 gal. Entered as one section from 3.5 ft to 8 ft, it would come to 22,023 gal, about 13% too much.
An oval pool with straight sides
Many above-ground oval pools are two half circles joined by straight sides. For one 15 ft × 30 ft, enter a rectangle 15 ft × 15 ft (the length minus the width) and a circle 15 ft across. With water 3 ft 10 in deep, it holds 11,519 gal. The Oval shape with the same size gives 10,135 gal, because an ellipse has about 12% less area.
Metric dimensions
A pool 10 m × 5 m, 1.2 m to 2 m deep: 10 × 5 × 1.6 = 80 m³, or 80,000 L (21,134 gal).
FAQ
Multiply the surface area by the average depth, then convert. For example, a 40 ft × 20 ft pool that is 3 ft to 8 ft deep holds about 32,914 gal. A 24 ft round above-ground pool with 4 ft of water holds about 13,536 gal.
Add the water depth at the shallow end and at the deep end, and divide by 2. A pool 3 ft deep at one end and 8 ft at the other has an average depth of 5.5 ft.
Split it into a rectangle and a circle. The rectangle is the overall length minus the width by the width, and the circle has a diameter equal to the width. A 15 ft × 30 ft pool is a 15 ft × 15 ft rectangle plus a 15 ft circle. With water 3 ft 10 in deep, it holds about 11,519 gal. Entered as an Oval of the same size, it would come to 10,135 gal, because an ellipse has less area.
It's a rounded value. A cubic foot holds 1,728 ÷ 231 = 7.48052 US gallons, so 7.5 gives a result about 0.26% higher. The calculator uses the exact value.
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