Pool Volume Calculator
Calculate how many gallons of water your pool holds.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Knowing your pool's volume is essential for chemical dosing, heater sizing, pump selection, and water cost estimates. This calculator handles rectangular, circular, and oval pools with variable depth. Here is how to use it:
- Select your pool shape. Choose rectangle for standard rectangular or square pools, circle for round above-ground or in-ground pools, or oval for oval-shaped pools.
- Enter your dimensions. For rectangular and oval pools, enter the length and width in feet. For circular pools, enter the diameter. Measure from the inside walls of the pool, not the outside edge of the coping.
- Enter the depth. Provide the shallow end depth and the deep end depth. The calculator averages these two values. If your pool has a uniform depth, enter the same number for both fields.
Results update instantly. The primary result shows total gallons, with cubic feet, liters, and average depth in the breakdown section. Use the Share button to send your pool specs to a contractor or pool supply store, or Copy the result for your records.
The formulas used: for rectangles, length x width x average depth x 7.48 gallons per cubic foot. For circles, pi x (diameter/2)^2 x average depth x 7.48. For ovals, pi x (length/2) x (width/2) x average depth x 7.48. All calculations run in your browser with no data sent anywhere.
About Pool Volume
Pool volume is measured in gallons (US) and determines how much chemical treatment your pool requires. An average residential pool holds between 10,000 and 30,000 gallons. Knowing the exact volume helps you calculate the correct amount of chlorine, shock treatment, algaecide, and pH balancers to add. Overdosing wastes money and can irritate swimmers. Underdosing leaves the water unsafe.
Pool volume also affects equipment sizing. Pool pumps are rated for a specific flow rate, and the pump must be able to turn over the entire pool volume at least once every 8-12 hours. Heaters are rated in BTU, and a larger volume requires more BTU to raise the water temperature by one degree.
Frequently Asked Questions
How many gallons of water are in my pool?
A standard 12x24 foot rectangular pool with an average depth of 5 feet holds about 10,800 gallons. A 16x32 foot pool at the same depth holds about 19,200 gallons. A 20-foot round pool at 4 feet deep holds about 9,400 gallons. The exact volume depends on your pool's shape, dimensions, and depth profile. Use the calculator above by entering your specific measurements for an accurate result.
How do you calculate pool volume?
For a rectangular pool: multiply length x width x average depth (in feet) to get cubic feet, then multiply by 7.48 to convert to gallons. For a round pool: use pi x radius squared x average depth x 7.48. For an oval pool: use pi x (length/2) x (width/2) x average depth x 7.48. The average depth is typically the shallow end plus the deep end, divided by two.
How much water does a pool use per year?
A typical residential pool loses about 2-4 inches of water per week to evaporation, depending on climate, wind, and sun exposure. For a 15,000 gallon pool, that translates to roughly 7,000-15,000 gallons of makeup water per season. A pool cover can reduce evaporation by 90-95%. Splash-out, filter backwashing, and leaks add to water consumption. Total annual water use for pool maintenance (not counting the initial fill) typically ranges from 8,000 to 20,000 gallons.
How much chlorine do I need for my pool?
The general guideline is to maintain 1-3 ppm (parts per million) of free chlorine. For a 10,000 gallon pool, adding about 2 ounces of liquid chlorine (sodium hypochlorite at 12.5%) raises the level by approximately 1 ppm. For granular shock (calcium hypochlorite at 65%), you need about 1 pound per 10,000 gallons to raise levels by roughly 10 ppm. Always test your water first and follow the product label directions for your specific pool volume.