What's under the hood: the geometry we use, why the floor shape changes the answer, and the line we won't cross on accuracy.
Most pool-volume calculators ask for length, width, and one depth, then multiply. That overstates volume for any pool that isn't a uniform-depth box — which is most pools. We do the geometry properly, shape by shape, and we're honest about what a number can and can't tell you.
Every volume starts with the pool's surface area, and the right formula depends on the shape:
A pool with a shallow shelf and a separate deep end holds far less water than its deepest point suggests. Averaging the shallow and deep depths can overstate volume by 20% or more — enough to throw off every chemical dose. That's why we ask for the floor profile (flat, sloped, hopper/deep-end, or spa) and compute the true average depth from the actual floor, not a guess.
Volume is surface area × average depth, in cubic feet. We convert to US gallons using 1 cubic foot = 7.48 gallons, and to litres, imperial gallons, and cubic metres from there. Every calculator shows all five units so you don't have to convert anything yourself.
Some numbers shouldn't be presented as exact, so we don't. We give pump-sizing as a horsepower range, not a single figure, because pumps are matched to a performance curve. We size filters by flow rate and show the NSF maximums. We never compute a chemical dose — we hand you to your test kit — and we never estimate what a pool does to your home's resale value, because that's intensely local. When a result is an estimate, we say so.
Our results are accurate for the dimensions you enter, but real pools have irregular floors, fill levels, and construction tolerances. Treat every figure as a strong estimate for planning, and verify before you buy materials or dose chemicals.
Every calculator shows its formula and a step-by-step walkthrough using your own numbers, and you can download a PDF, copy the result, or embed the calculator on your own site. The math isn't hidden — you can audit it.