Swimming Pool Volume Calculator

Knowing your pool's exact water volume is essential for safe and efficient pool management. Chemical dosing — chlorine, pH adjusters, algaecide, and shock treatments — must always be calculated based on total gallons, and using the wrong volume leads to under- or over-treated water. Volume figures are also needed to estimate heating costs, calculate water bill impacts when filling or refilling, and size a pump or filtration system correctly. Enter your pool's length, width, and average depth to instantly get the total volume in US gallons, liters, and cubic feet, covering all the units your pool supplier, chemical labels, or equipment manuals might require. Most backyard rectangular pools hold between 10,000 and 30,000 gallons of water, depending on size and depth. Knowing the precise volume lets you calculate exactly how much chlorine to add after a rain event, how much water is lost to evaporation or splash-out each week, and how long it will take to fill or drain the pool at a known flow rate. This calculator is designed specifically for rectangular pools; for round or oval pools, a shape correction factor applies.

The calculator first multiplies the pool's length, width, and average depth together to produce the total volume in cubic feet (length × width × depth = ft³). This works because a rectangular pool is a rectangular prism, and volume of a rectangular prism is simply the product of its three dimensions. The cubic foot result is then converted to US gallons by multiplying by 7.48052 — the number of gallons in one cubic foot. The same cubic foot value is also multiplied by 28.3168 to produce the equivalent in liters, since one cubic foot equals 28.3168 liters. For pools with a sloped bottom (shallow end and deep end), use the average depth, calculated as (shallow depth + deep depth) ÷ 2, to get an accurate volume estimate.