How this pool volume calculator works
A pool's volume is its surface area multiplied by the average depth of the water. The surface area depends on the shape: a rectangular pool is length × width, a round pool is π × (diameter ÷ 2)², and an oval pool is the ellipse area π × (length ÷ 2) × (width ÷ 2). Multiply that area by the average depth and you have the volume in cubic feet (or cubic meters if you measured in meters).
Pools rarely have a single depth, so the calculator works from the average depth. If your pool slopes from a shallow end to a deep end, switch the depth input to "Shallow + deep ends" and the tool averages them for you: average = (shallow + deep) ÷ 2. To turn volume into capacity it converts cubic feet to US gallons by multiplying by 7.48052, and cubic meters to liters by multiplying by 1000 — then shows gallons, liters, cubic feet and cubic meters together.
Reference note: these conversion factors are used. The oval (ellipse) area uses π ≈ 3.14159265.
| Conversion | Multiply by |
|---|---|
| Cubic feet → US gallons | 7.48052 |
| Cubic feet → liters | 28.3168 |
| Cubic meters → liters | 1000 |
| Cubic meters → US gallons | 264.172 |
Frequently asked questions
- How many gallons is my pool?
- Find your pool's volume in cubic feet, then multiply by 7.48 to get US gallons. For a rectangular pool, volume is length × width × average depth. A 32 ft × 16 ft pool with a 5 ft average depth holds 2,560 cubic feet, which is about 19,150 gallons.
- How do I find the average depth of a pool?
- If the bottom slopes from a shallow end to a deep end, add the shallow depth and the deep depth and divide by two: average = (shallow + deep) ÷ 2. For a pool that is 3 ft at the shallow end and 8 ft at the deep end, the average depth is (3 + 8) ÷ 2 = 5.5 ft.
- How do I calculate the volume of a round pool?
- Use the area of the circle times the average depth: volume = π × (diameter ÷ 2)² × average depth. A round pool 24 ft across with a 4 ft average depth holds π × 12² × 4 ≈ 1,810 cubic feet, or about 13,540 gallons.
- How many gallons are in a cubic foot?
- One cubic foot holds about 7.48 US gallons (7.48052 to be precise). So once you know a pool's volume in cubic feet, multiply by 7.48 to get US gallons. To get liters instead, multiply cubic feet by 28.3168.
- Why does pool volume matter for chemicals?
- Most pool chemicals — chlorine, shock, algaecide, pH adjusters — are dosed per a set number of gallons. If you overestimate the volume you waste product, and if you underestimate it the water can be over-treated. Knowing the gallons lets you dose accurately and keep the water balanced.
- What is the difference between a rectangular and an oval pool calculation?
- A rectangular pool uses length × width for its surface area, while an oval pool uses the ellipse area π × (length ÷ 2) × (width ÷ 2). For the same length and width an oval holds about 78.5% of the rectangular volume, because its rounded ends remove the corners.