Pool Volume Calculator
Your pool's gallonage is the starting point for every chemical dose, salt addition, and pump or heater sizing. Measure in feet, pick your shape, get gallons.
How to measure average depth
- Sloped floor: Average depth = (shallow end + deep end) ÷ 2. A 3 ft shallow end and 6 ft deep end = 4.5 ft average.
- Kidney / free-form pools: multiply the rectangular result by roughly 0.85 to account for the curves.
- Metric? 1 cubic meter = 264.2 gallons; 1 ft = 0.3048 m.
The formulas we use
- Rectangular: Length × Width × Avg Depth × 7.48
- Round: 3.14 × Radius² × Avg Depth × 7.48
- Oval: Length × Width × Avg Depth × 5.9
- Kidney: (Length × Width − 0.45 × Length + 0.45 × Width... simplified) Length × Width × Avg Depth × 7.48 × 0.85
7.48 gallons = one cubic foot. Water in a 16×32 pool with 4.5 ft average depth: 16 × 32 × 4.5 × 7.48 ≈ 17,240 gallons.
Frequently asked questions
Why do I need to know my pool volume?
Chemical dosing, salt additions, pump sizing and heater sizing are all calculated per gallon. Without an accurate volume, you're guessing — and over-dosing chlorine or acid is the fastest way to ruin a swim weekend.
My pool has a deep end and a tanning ledge. What depth do I use?
Use the true average: add the shallowest and deepest points and divide by two. For irregular pools with a large tanning ledge, estimate slightly lower than the straight average.
How accurate does the number need to be?
Within about 10% is fine for dosing. When in doubt for chemical additions, dose slightly under, re-test, then top up.