Pool Volume Calculator
Select your pool shape and enter the dimensions to calculate the total volume in gallons, cubic feet, and liters. The fill time estimate assumes a standard garden hose flow rate of 500 gallons per hour.
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How Pool Volume Is Calculated
Rectangular pools use the simplest formula: length times width times average depth gives you cubic feet. Circular pools use the circle area formula (pi times radius squared) multiplied by depth. Oval pools use the ellipse area formula (pi times half-length times half-width) multiplied by depth.
Converting cubic feet to gallons is straightforward: multiply by 7.48052. One cubic foot holds exactly 7.48052 US gallons. For liters, multiply cubic feet by 28.3168. These conversion factors are standardized and precise.
The average depth is critical for accuracy. Most residential pools slope from shallow to deep, so the average depth sits between those two extremes. Measuring at three or four points along the slope and averaging gives a better result than using just the two ends.
Why Pool Volume Matters for Maintenance
Every pool chemical dosage depends on the total water volume. Chlorine, pH adjusters, algaecide, and stabilizer all specify the amount to use per a certain number of gallons. Overestimating your volume leads to under-treating the water, while underestimating can cause chemical levels to spike dangerously.
Pump and filter sizing also relies on pool volume. The general rule is that your filtration system should cycle all the water through the filter at least once every 8 to 12 hours. An undersized pump cannot keep up with a large pool, leading to cloudy water and increased algae risk.
Salt chlorine generators, UV sanitizers, and ozone systems are all rated by gallons as well. Installing the wrong capacity means inefficient operation and higher energy costs. Getting the volume right from the start saves headaches throughout the pool season.
Filling Your Pool: Time and Cost
A standard garden hose delivers about 500 gallons per hour. For a typical 15,000-gallon residential pool, that means roughly 30 hours of continuous running to fill it from empty. Larger pools with 25,000 or more gallons can take two to three full days.
Water costs vary by region, but the average US rate is about 0.005 dollars per gallon. Filling a 15,000-gallon pool costs roughly 75 dollars in water alone. Some municipalities offer pool fill discounts or allow a sewer credit since the water does not go down the drain.
If speed matters, a water delivery truck can fill a pool in a few hours. Delivery costs between 200 and 600 dollars depending on location and volume. This option is popular in areas with well water that cannot keep up with pool-fill demand or where well pumps could be damaged by extended continuous use.
Frequently Asked Questions
How do I find the average depth of my pool?
Add the shallow end depth and the deep end depth, then divide by two. For a pool that goes from 3 feet to 8 feet, the average depth is 5.5 feet. If the bottom is not a straight slope, measure at several points and average those readings.
Why is knowing pool volume important?
Pool volume determines the correct amount of chemicals to add, the right pump and filter size, and how long your filtration system needs to run. Using chemicals based on an incorrect volume can lead to unsafe water conditions or wasted product.
How accurate is the fill time estimate?
The estimate assumes a typical garden hose flowing at about 500 gallons per hour. Your actual hose flow rate depends on water pressure and hose diameter. A 5/8-inch hose at 40 psi delivers around 480 gallons per hour, which is close to this estimate.
How do I convert pool volume to metric?
One cubic foot equals 28.3168 liters and 7.48052 US gallons. This calculator converts automatically, so you get all three units at once without needing separate conversion steps.
What about irregularly shaped pools?
For freeform pools, divide the pool into simpler shapes like rectangles and semicircles. Calculate each section separately using the appropriate formula, then add them together. Use the average depth for each section.