Pool Volume Calculator
Knowing your pool's exact water volume is essential for proper chemical treatment, equipment sizing, and compliance with health department requirements. Use this calculator to determine the volume of your pool in gallons based on its dimensions and shape.
Calculate Pool Volume
Volume is approximate. Irregular shapes, steps, benches, and slope variations will affect actual volume. For chemical treatment, consider having your pool professionally measured.
How Pool Volume Is Calculated
Pool volume depends on the surface area multiplied by average depth. The average depth is typically calculated as the midpoint between the shallow and deep ends, though pools with a gradual slope will have a more uniform depth distribution.
Volume Formulas by Shape
- Rectangular: Length × Width × Average Depth × 7.48 gallons/ft³
- Circular: π × (Radius)² × Average Depth × 7.48
- Oval: π × (Long Axis / 2) × (Short Axis / 2) × Average Depth × 7.48
- Kidney / Freeform: Uses 85% of the rectangular equivalent (Length × Width × 0.85)
Why Accurate Volume Matters
An accurate pool volume calculation is necessary for:
- Chemical dosing — chlorine, pH adjusters, algaecides, and salt are all dosed per gallon
- Pump and filter sizing — turnover rate (typically 8–12 hours) depends on volume
- Heater sizing — BTU requirements scale directly with water volume
- Health department compliance — commercial pools must document exact volume for chemical logs
Frequently Asked Questions
How many gallons does an average residential pool hold?
Most residential pools hold between 10,000 and 25,000 gallons. A typical 15 × 30 foot rectangular pool with an average depth of 5 feet holds approximately 16,830 gallons.
Does pool volume include the plumbing?
Standard volume calculations cover the pool basin only. The plumbing system typically adds 50–200 gallons depending on pipe runs, filter housing, and heater volume. For routine chemical treatment, basin volume alone is sufficient.
How do I measure pool depth if the bottom slopes?
Measure the depth at the shallowest point and the deepest point. The calculator uses the average of these two values. For pools with a flat bottom section in the middle, this method slightly overestimates volume, which provides a conservative margin for chemical dosing.