Spa Volume Calculator
Calculate hot tub or spa volume from diameter and depth. Result in gallons.
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Quick tips
Most round spas: measure inside diameter and water depth in feet. Typical hot tubs are 300–500 gallons.
- Typical range: 1–3 ppm chlorine
- Recommended pH: 7.2–7.6
- Test water regularly
WaterBalanceTools provides practical calculators and guides for pool and hot tub water chemistry. These tools are designed to help maintain safe chlorine, pH, and total alkalinity within a healthy water balance.
Last updated: April 2026