Pool Volume Calculator
From the builder's plans or a measured sketch.
Same as shallow for a flat floor.
Pool volume
22,023 gallons
A rectangular pool with 512 sq ft of surface and an average depth of 5.75 ft holds about 22,023 gallons.
- Surface area
- 512 sq ft
- Average depth
- 5.75 ft
- Volume
- 2,944 cu ft
- In liters
- 83,365 L
How it's calculated
Pool volume is surface area multiplied by average depth. The calculator works out the surface area for your shape, multiplies it by the average depth and converts cubic feet to gallons (or cubic meters to liters).
| Shape | Surface area |
|---|---|
| Rectangle | length × width |
| Round | 3.1416 × (diameter ÷ 2)² |
| Oval | 3.1416 × (length ÷ 2) × (width ÷ 2) |
| Kidney | 0.45 × (width A + width B) × length |
| Freeform | measured area |
The 7.48 factor comes from the definition of the US gallon (231 cubic inches; NIST Handbook 44) divided into the 1,728 cubic inches of a cubic foot. The kidney formula is a long-standing pool-industry approximation: the two widths are measured across the widest part of each lobe. The oval formula is a true ellipse; if your "oval" above-ground pool has straight sides and round ends, it holds slightly more than this result.
Worked example
A 16 × 32 ft rectangular in-ground pool, 3.5 ft at the shallow end and 8 ft at the deep end:
- Surface area: 16 × 32 = 512 sq ft.
- Average depth: (3.5 + 8) ÷ 2 = 5.75 ft.
- Cubic feet: 512 × 5.75 = 2,944 cu ft.
- Gallons: 2,944 × 7.48 = 22,023 gallons (83,365 liters).
A kidney pool 30 ft long, 10 ft and 14 ft across its two lobes, 3.5 to 6 ft deep: 0.45 × 24 × 30 = 324sq ft × 4.75 ft average = 1,539 cu ft, or about 11,513 gallons.
How to measure your pool
- Measure length and width at the water line, inside the walls, not at the outer edge of the coping.
- Measure depth from the water surface to the floor, not from the deck. A pole with a tape measure works well.
- For a freeform pool, sketch it as rectangles and half-circles, add the areas, and use the freeform option.
- Steps, benches and tanning ledges reduce volume. Ignore them for small pools; subtract them for large ledges.
Once you know the volume, use it to dose chemicals with the chlorine calculatorand to size circulation with the pump size calculator.
Gallons in common pool sizes
Rectangular in-ground pools at a typical average depth:
| Size (ft) | Avg depth | Gallons | Liters |
|---|---|---|---|
| 12 × 24 | 4.5 ft | 9,695 | 36,699 |
| 14 × 28 | 5 ft | 14,662 | 55,501 |
| 15 × 30 | 5 ft | 16,831 | 63,713 |
| 16 × 32 | 5.5 ft | 21,065 | 79,740 |
| 18 × 36 | 5.5 ft | 26,661 | 100,921 |
| 20 × 40 | 5.5 ft | 32,914 | 124,594 |
Round above-ground pools with 4 ft of water:
| Diameter | Gallons | Liters |
|---|---|---|
| 15 ft | 5,288 | 20,016 |
| 18 ft | 7,614 | 28,823 |
| 21 ft | 10,364 | 39,231 |
| 24 ft | 13,536 | 51,241 |
| 27 ft | 17,132 | 64,852 |
| 30 ft | 21,151 | 80,064 |
Values computed with the formulas above; 7.5 gal per cu ft.
Frequently asked questions
How many gallons is a 16 x 32 pool?
With a 3.5 ft shallow end and an 8 ft deep end (5.75 ft average), a 16 × 32 ft rectangular pool holds about 22,023 gallons. With a flat 5 ft depth it holds about 19,150 gallons. The depth matters as much as the length and width, so measure both ends.
How do I calculate the gallons in a round pool?
Multiply 3.14 × radius × radius × average depth (all in feet) to get cubic feet, then multiply by 7.48. A 24 ft round pool with 4 ft of water: 3.1416 × 12 × 12 × 4 = 1,810 cu ft × 7.48 = about 13,536 gallons.
How many gallons are in a 24 ft above-ground pool?
It depends on the water depth, not the wall height. Most 52-inch walls are filled to about 4 ft, which gives about 13,536 gallons. Each extra 6 inches of water adds roughly 1,692 gallons.
How do I find the average depth of a pool with a deep end?
Add the shallow-end depth and the deep-end depth and divide by 2. For a 3.5 ft shallow end and an 8 ft deep end, the average is 5.75 ft. If the deep end is a short hopper rather than a long slope, the real average is a little lower, so treat the result as a slight overestimate.
How accurate is a pool volume calculator?
For simple shapes measured carefully, expect to be within about 5% of the real volume. Freeform pools, steps, benches and curved walls add more uncertainty. The most accurate method is to read the water meter before and after filling (or topping up a known depth).
How many gallons are in a cubic foot of water?
One cubic foot holds 7.48 US gallons (a US gallon is defined as 231 cubic inches, and a cubic foot is 1,728 cubic inches). One cubic meter holds 1,000 liters, or about 264 US gallons.
Related calculators
- Pool Chlorine CalculatorDose for liquid, cal-hypo, dichlor or trichlor.
- Pool Salt CalculatorPounds or kg of salt and number of bags.
- Pool Pump Size CalculatorRequired GPM and total dynamic head.
- Pool Fill Cost CalculatorTap water vs. truck delivery for your pool.
- Pool Turnover Rate CalculatorHours per turnover, or GPM for a target turnover.
See all Pool Equipment Sizing Calculators.