What Is the Pool Volume Calculator?
This tool estimates how much water a rectangular swimming pool holds, in US gallons. Knowing your pool's volume is essential for correctly dosing chlorine, shock, algaecide, and other chemicals, as well as for sizing pumps, heaters, and filters. Enter your pool's length, width, and the depth at the shallow and deep ends, and the calculator returns the total capacity along with surface area and a metric (liter) equivalent.
How to Use It
Measure all dimensions in feet. Enter the pool's length and width, then the water depth at the shallow end and the deep end. If your pool has a flat bottom, enter the same depth in both fields. The calculator averages the two depths, multiplies by the surface area to get cubic feet, and converts to gallons using the factor 7.48 gallons per cubic foot.
The Formula Explained
The core equation is $$\text{Gallons} = \text{Length} \times \text{Width} \times \text{Average Depth} \times 7.48$$ One cubic foot of water equals approximately 7.48 US gallons. The average depth is simply \(\frac{\text{shallow} + \text{deep}}{2}\), which works well for pools whose floor slopes evenly from one end to the other.
Worked Example
Consider a pool 32 ft long and 16 ft wide, with a shallow end of 3 ft and a deep end of 8 ft. The average depth is $$\frac{3 + 8}{2} = 5.5 \text{ ft}$$ Surface area is $$32 \times 16 = 512 \text{ sq ft}$$ Volume is $$512 \times 5.5 = 2{,}816 \text{ cubic feet}$$ Multiplying by 7.48 gives about 21,064 gallons.
FAQ
Is this for rectangular pools only? Yes — the formula assumes a rectangular surface. For round or oval pools you would use a different area formula.
Why 7.48? There are 7.48052 US gallons in one cubic foot; we round to 7.48 for practical estimates.
What if my pool floor is flat? Enter the same value for both the shallow and deep depths, and the average will equal that depth.
