What this calculator does
The Round Pool Volume Calculator estimates how much water a circular above-ground or in-ground pool holds, based on its diameter and average depth.
The formula
A round pool is treated as a cylinder: Volume = π × r² × average depth, where r is half the pool’s diameter. The result in cubic feet is converted to U.S. gallons using 1 cubic foot ≈ 7.4805 gallons, and to liters using 1 gallon ≈ 3.78541 liters.
If your pool has a sloped bottom (shallow end to deep end), use the average of the shallow and deep depths as the "average water depth" input for a reasonably accurate estimate.
- Use this figure for planning chemical dosing, fill time, or heater sizing.
- For precise chemical treatment, always follow the product label’s recommended dosage per gallon, and use a test kit to confirm water balance.
Last reviewed August 2026