Pool Volume Calculator
Find how many gallons of water your swimming pool holds — for chemical dosing and equipment sizing.
Results are estimates. Steps, benches, and curved walls change the true volume. Round when dosing chemicals and follow the product instructions.
How to Measure a Pool
Pool volume is the surface area multiplied by the average water depth.
Pool shape
Choose rectangular, round, or oval and enter the dimensions in feet. For a round pool that's the diameter; for rectangular and oval it's the length and width.
Shallow and deep depth
Enter the water depth at the shallow end and the deep end. The calculator averages them — if your pool is one depth throughout, enter the same number twice.
Common Mistakes to Avoid
- Using the deep-end depth alone. Volume uses the average of the shallow and deep ends, not the maximum.
- Measuring the pool, not the water. Use the actual water depth, which is below the top of the wall.
- Over-dosing chemicals. An inflated volume leads to wasted chemicals; an undersized one leaves the water unbalanced.
- Ignoring shape. A round pool holds about 21% less than a square of the same width — pick the right shape tab.
Frequently Asked Questions
Multiply surface area by average depth for cubic feet, then by 7.48 for gallons.
Add the shallow and deep depths and divide by two.
It sets the correct dose for chlorine and other chemicals and helps size a pump, heater, and filter.
Roughly 19,000 gallons at a 5 ft average depth, about 15,300 at a 4 ft average depth.
Treating the pool as a simple shape is close; steps and curves shift it slightly, so round when dosing.