Swimming Pool Calculator
Calculate rectangular pool volume, water capacity, average depth, and a planning-level construction cost from common dimensions.
About the swimming pool calculator
A pool volume estimate is central to planning circulation, heating, chemical dosing, filling time, and operating cost. This swimming pool calculator models a rectangular pool with a floor that changes evenly between shallow and deep ends. It averages the two depths, multiplies that value by length and width, and reports cubic feet. The volume is then multiplied by 7.48052 to estimate US gallons. Using average depth is more representative than using either endpoint alone when the floor has a consistent slope. Pools with diving wells, benches, beach entries, curved walls, or multiple depth zones need a more detailed method. Divide those designs into simple sections, estimate each section separately, and add the results. Plans supplied by a pool designer or builder should take priority whenever precise equipment sizing or code compliance is required. Water capacity informs pump and filter selection, but geometric capacity is not the same as operating capacity. The normal waterline sits below the coping, and stairs, ledges, people, and equipment displace water. Even so, a dimensional estimate is a useful baseline for comparing filter turnover rates and calculating an initial chemical dose. Always follow product labels and test the water rather than relying solely on a calculated dose. The cost estimate multiplies the pool’s plan area by the entered cost per square foot. This is intentionally a broad budgeting method. Actual project prices depend on excavation, soil and groundwater conditions, shell type, reinforcement, plumbing, electrical work, decking, access, finishes, equipment, permits, landscaping, and regional labor. The result should be treated as an early comparison figure, not a contractor quotation. Measure finished internal dimensions when estimating water. If measurements come from an excavation before the shell and finish are installed, the completed pool may be smaller. Use the same unit for all dimensions and verify whether supplier capacities are stated in US gallons, imperial gallons, liters, or cubic meters. With consistent inputs, the calculator gives homeowners and pool professionals a quick, transparent estimate that can support design conversations, equipment research, delivery planning, and preliminary budgets.
Swimming pool examples
Each example assumes a straight, evenly sloped floor.
| Pool dimensions | Calculated capacity and cost | Context |
|---|---|---|
| 30 ft by 15 ft, depths 3 ft and 7 ft, rate $75 | 2,250 cu ft, 16,831.17 gal, $33,750 | Typical rectangular residential pool. |
| 20 ft by 10 ft, depths 4 ft and 6 ft, rate $90 | 1,000 cu ft, 7,480.52 gal, $18,000 | Compact backyard pool. |
| 40 ft by 20 ft, depths 3.5 ft and 8.5 ft, rate $110 | 4,800 cu ft, 35,906.5 gal, $88,000 | Large pool with a six-foot average depth. |
How to calculate pool volume
- Measure the finished internal length and width at the water line.
- Measure the shallow and deep depths from the water line to the floor.
- Enter a local planning cost per square foot of pool area.
- Select Calculate pool to view average depth, volume, gallons, and cost.
- Confirm final equipment and construction requirements with qualified professionals.
Swimming pool calculator FAQ
How is average pool depth calculated?
The shallow and deep depths are added and divided by two. This method is appropriate for a floor with a reasonably uniform slope between the two ends.
How many gallons are in one cubic foot?
One cubic foot contains approximately 7.48052 US gallons. Imperial gallons use a different conversion, so check which gallon unit an equipment specification uses.
Will the calculated capacity equal the actual fill?
Actual water volume is usually lower because the waterline is below the rim and steps or benches displace water. A fill meter provides a more exact operating capacity.
What does the construction cost include?
The result is only plan area multiplied by your entered rate. Obtain itemized quotes that address excavation, shell, systems, finishes, permits, access, and site restoration.
Can this calculator size a pool pump?
Capacity is one input for pump selection, but desired turnover time and hydraulic resistance also matter. A pool professional should verify flow, filter, pipe, and electrical requirements.