Pool Volume Calculator
Enter your pool’s shape and dimensions. Get total gallons (or liters), surface area, and average depth. Five shape modes handle most residential pools: rectangle, circle, oval, kidney, and a custom-area mode for freeform shapes. Shallow and deep depth are separate inputs, so the math handles a 3.5-ft to 8-ft (107-cm to 244-cm) sloped inground pool and a 4-ft (122-cm) uniform-depth above-ground round the same way.
Results
Estimates only. Actual fill volume varies with tile thickness, coving, and tanning ledges. Confirm with your pool builder or check your gallon-rated heater and filter sizing chart against your final volume. TakeoffCalc isn't responsible for chemical-dosage or equipment-sizing errors.
How to use this calculator
- 01Pick a shape: rectangle, circle, oval, kidney, or custom area.
- 02Enter your dimensions. For rectangle and oval, that's length and width. For circle, diameter. For kidney, overall length plus the two widest widths.
- 03Enter shallow and deep depths. For a uniform-depth pool, enter the same value in both fields.
- 04Read the total gallons (liters in metric) at the top of the results panel. That's the headline number for sizing heaters, pumps, and chemical doses.
- 05Compare your result against the Common Pool Sizes table to sanity-check against industry typicals.
Understanding the math
First, surface area from shape:
Rectangle area = length × width Circle area = π × (diameter / 2)² Oval area = π × (length / 2) × (width / 2) Custom = area entered directly
Second, average depth and volume:
average depth (ft) = (shallow inches + deep inches) / 2 / 12 volume (cu ft) = area × average depth
Third, gallons:
gallons = volume (cu ft) × 7.4805 (7.4805 = US liquid gallons per cubic foot, NIST) Kidney (industry formula): gallons = (width 1 + width 2) × length × 0.45 × average depth (ft) × 7.5
Worked example: a 30 × 15 ft (9.1 × 4.6 m) rectangle pool with a shallow depth of 42 in (107 cm) and deep depth of 72 in (183 cm). Area is 30 × 15 = 450 sq ft (42 m²). Average depth is (42 + 72) / 2 = 57 in. Convert to feet: 57 / 12 = 4.75 ft (1.45 m). Volume is 450 × 4.75 = 2,137.5 cu ft (60.5 m³). Gallons is 2,137.5 × 7.4805 ≈ 15,990 gallons (60,529 L).
Common pool sizes
A few industry typicals to compare against. Above-ground rounds use uniform depth. Inground rectangles slope from shallow to deep. Kidney uses the dedicated industry formula.
| Description | Shape | Dimensions | Depth (avg) | Gallons |
|---|---|---|---|---|
| Above-ground round, small | Circle | 15 ft diameter | 4 / 4 ft | 5,288 gal |
| Above-ground round, large | Circle | 27 ft diameter | 4 / 4 ft | 17,132 gal |
| Inground rectangle, small | Rectangle | 10 × 20 ft | 3.5 / 5 ft | 6,358 gal |
| Inground rectangle, standard | Rectangle | 16 × 32 ft | 3.5 / 8 ft | 22,023 gal |
| Inground rectangle, large | Rectangle | 20 × 40 ft | 4 / 9 ft | 38,899 gal |
| Kidney, residential | Kidney | L=32, W1=16, W2=12 ft | 3.5 / 8 ft | 17,388 gal |
Frequently asked questions
How many gallons is my pool?
To work it out by hand: get the surface area, multiply by average depth in feet, then multiply by 7.4805 (US liquid gallons per cubic foot). For a sloped pool, average depth is (shallow + deep) / 2. A 30 × 15 ft rectangle pool with a 3.5-ft to 6-ft slope is 450 sq ft × 4.75 ft × 7.4805 ≈ 15,990 gallons.
Or skip the math and use the calculator above. It covers all five shapes including the kidney formula, which uses different constants than the geometric shapes.
How many gallons does a typical inground pool hold?
A standard 16 × 32 ft inground rectangle with a 3.5-ft to 8-ft slope holds about 22,023 gallons (83,366 L). A smaller 10 × 20 ft pool runs about 6,358 gallons (24,068 L). A larger 20 × 40 ft pool pushes past 38,899 gallons (147,248 L). A residential kidney with a 32-ft length and 16/12-ft widths runs about 17,388 gallons (65,821 L) using the industry kidney formula. The Common Pool Sizes table on this page covers more shapes and dimensions.
Why are there separate shallow and deep depth fields?
Most inground pools slope from a shallow end to a deep end. A 16 × 32 ft pool typically runs 3.5 ft at the shallow end and 8 ft at the deep end. The math averages the two depths to get an effective uniform depth, then multiplies by surface area to get volume. For a uniform-depth pool (most above-ground rounds, some lap pools), enter the same value in both fields and the average is just that value. The two-field approach handles both cases without forcing you to pre-compute an average.
Can I use this calculator with metric measurements?
Yes. Toggle the unit system at the top of the form. Inputs flip from feet and inches to meters and centimeters. Outputs flip from gallons to liters and cubic feet to cubic meters. The math runs in imperial internally and converts at the input and output edges, so the precision stays the same in either system.
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