Pool Volume Calculator
Calculate swimming-pool volume in US gallons, liters, cubic meters and cubic feet for rectangular, round, oval or measured plan areas. Add flow rate and water price for fill time and cost.
Pool volume formulas
Average depth = (shallow depth + deep depth) ÷ 2
Pool volume = plan area × average depth
- Rectangle area: length × width
- Round area: π × (diameter ÷ 2)²
- Oval area: π × long axis × short axis ÷ 4
Conversions used: 1 cubic foot = 7.48051948 US gallons = 28.316846592 liters; 1 cubic meter = 1,000 liters = approximately 264.172052 US gallons.
Worked examples
| Shape and dimensions | Average depth | Calculated volume |
|---|---|---|
| Rectangle, 30 × 15 ft | 4.5 ft | 15,148.052 US gal |
| Round, 24 ft diameter | 4 ft | 13,536.429 US gal |
| Oval, 30 × 15 ft | 4.5 ft | 11,897.252 US gal |
| Rectangle, 10 × 5 m | 1.5 m | 75,000 L |
| Round, 6 m diameter | 1.2 m | 33,929.201 L |
| Measured plan area, 120 m² | 1.4 m | 168,000 L |
How to calculate pool water volume
- Select US or metric units and the closest plan shape.
- For an irregular pool, use a measured water-surface area instead of an arbitrary shape factor.
- Measure shallow and deep water depths. Enter the same value twice for a flat floor.
- Add an actual fill flow rate if you want an approximate filling time.
- Enter the water rate per 1,000 gallons or cubic meter to estimate the commodity cost.
Important limitations
- Average depth is an approximation when the floor profile is not a simple uniform slope.
- The dimensions should follow the waterline, not the outer deck or excavation.
- Steps, benches, spas, overflow tanks, plumbing and freeboard are not automatically added or subtracted.
- Fill time assumes constant flow and excludes interruptions, pressure changes, evaporation and simultaneous drains.
- Water cost excludes sewer charges, delivery, heating, treatment chemicals and other utility fees.
- Do not use an estimated volume alone for chemical dosing or equipment selection; confirm the actual operating volume.
Related calculators
Frequently asked questions
How many gallons are in my pool?
Select a shape, enter waterline dimensions and shallow/deep depths, and read the US-gallon result. The same calculation also returns liters and cubic units.
How do I calculate a flat-bottom pool?
Enter the same value for shallow and deep depth. Their average will equal that constant depth.
What should I use for an irregular pool?
Measure or obtain the plan area and select Measured surface area. Multiply that area by a representative average depth, then compare the estimate with plans or measured filling data.
Does the calculator include a spa or overflow tank?
No. Calculate separate connected volumes individually and add them only when they operate as one water system.
Can it estimate filling time?
Yes. Enter gallons per minute in US mode or liters per minute in metric mode. A zero flow leaves the time uncalculated.
Can I use the result for chemical treatment?
Use it only as a starting estimate. Chemical dosing should use a confirmed operating volume and the product instructions or qualified pool guidance.