Every pool owner's first mistake is estimating volume. It matters for chemical dosing, heating and filling — and it's the same geometry you learned in school, applied to a hole in the ground.
Footprint × depth
All pool shapes reduce to footprint times depth. The rectangle is the simplest; a circle brings π into it; an oval is an ellipse. The depth to use is the average where the bottom slopes, since the water forms a level surface regardless.
Why it has to be right
Chemical dosing is a ratio of treatment to volume. Overestimate and you over-treat — irritated eyes, wasted product. Underestimate and algae finds its opportunity. A reliable volume is the foundation of every pool-care routine.
Beyond the basics
Heating cost, pump sizing and water-balance software all key off volume. Irregular pools can be split into geometric shapes and summed — accurate enough to dose by, and a lot better than a guess.
Frequently asked questions
Multiply the pool's footprint by its average depth. Rectangle: L×W×D. Round: π × radius² × D. Oval: π × (L/2) × (W/2) × D. This calculator does all three shapes.
Chemical dosing is quoted per volume of water. An accurate figure means correct, safe chemical levels and avoids wasting expensive treatments.
Approximate it as a combination of rectangles and circles, calculate each part's volume and add them together — or take the slightly conservative average-depth route.