🏊 Pool Volume Calculator
Enter your pool's shape and dimensions to find how many gallons it holds — in US gallons, cubic feet, and litres. It's the foundation number for dosing chemicals and sizing your pump and heater.
💧 Shape & Size In, Gallons Out
What is a Pool Volume Calculator?
It converts the physical size of your pool into the volume of water it holds. Choose round, rectangular, or oval, give the key dimensions in feet and the depths at each end, and it applies the right area formula, multiplies by the average depth, and returns the total in three units at once.
Knowing your gallons is the starting point for balanced water: chlorine, salt, alkalinity, and heater calculations all scale directly with volume. Measure it accurately once and every other pool calculation gets easier — but remember these are estimates, so re-test your water after any addition.
❓ Frequently Asked Questions
Why do I need to know my pool's volume?
Almost every pool decision depends on it: how much chlorine, salt, or acid to add, what size pump and heater you need, and how long the filter must run. Dosing chemicals without an accurate gallon count is the most common cause of cloudy, unbalanced water, so it's worth measuring once and writing it down.
How do I measure the average depth?
For a pool that slopes evenly from a shallow end to a deep end, the average depth is simply (shallow depth + deep depth) ÷ 2 — which is exactly what this calculator uses. For a flat-bottomed above-ground pool, enter the same value for both ends. If your floor has a sudden drop or a hopper, the true average will be a little lower, so treat the result as a close estimate.
Do I measure in feet or metres?
Enter all dimensions in feet. The tool multiplies them to cubic feet, then converts to US gallons (× 7.48052) and litres. If you have metric measurements, convert them to feet first (1 metre ≈ 3.281 feet) before entering.
My pool is a freeform or kidney shape — what do I do?
Pick the shape closest to yours — oval usually approximates a rounded freeform pool best, and rectangular works for L-shapes if you calculate each rectangle and add them. The result is an estimate; for chemical dosing it's safe to round to the nearest few hundred gallons and always re-test the water after adding anything.