Pool Volume Calculator — How Many Gallons?
Enter your pool's dimensions and average depth to get the exact water volume in gallons and liters. No sign-up, no data stored.
Pool volume
How pool volume is calculated
The math is simple and exact — no assumptions to adjust for:
- Rectangular volume = length × width × average depth.
- Round volume = π × radius² × depth.
- Oval volume = length × width × 0.8 × average depth (standard oval area factor).
- Gallons = cubic feet × 7.48 (US gallons per cubic foot).
- Liters = gallons × 3.785.
Average depth is (shallow end + deep end) ÷ 2. Pool chemicals are dosed by volume, so knowing your gallons means the right amount of chlorine and shock every time.
Pool volume chart
Typical volumes for common pool sizes.
Common in-ground pools (average 5 ft depth)
| Pool size | Approx. gallons |
|---|---|
| 12×24 ft | ~10,800 |
| 16×32 ft | ~19,150 |
| 18×36 ft | ~24,200 |
| 20×40 ft | ~29,900 |
Round pools (average 4 ft depth)
| Diameter | Approx. gallons |
|---|---|
| 12 ft | ~3,390 |
| 15 ft | ~5,300 |
| 18 ft | ~7,640 |
| 24 ft | ~13,590 |
Last updated: October 2026 · Volumes assume a flat average depth; freeform pools vary slightly. Use the average-depth method (shallow + deep ÷ 2) for the closest estimate without a laser-level measurement.
Pool volume calculator FAQ
At 5 ft average depth, a 16×32 pool holds about 19,150 gallons. At 6 ft average, it's closer to 23,000 gallons. Measure your actual depths for a precise figure.
Add the shallow-end depth to the deep-end depth and divide by 2. A pool that's 3 ft at one end and 7 ft at the other has an average depth of 5 ft.
Follow the label on your specific product. As a guide, a standard shock dose is often about 1 pound per 10,000 gallons, and daily chlorine keeps free chlorine around 1–3 ppm. Always test, don't guess.
Yes — it's best broken into rectangles, circles, and ovals whose volumes you add together, or measured by a pool pro. The oval factor (×0.8) handles most gently-curved pools closely.
Yes. Use the actual water depth, not the wall height, since pools are usually filled a few inches below the coping. Measure to the waterline for chemical dosing.