Calculator

How many gallons is my pool?

Measure the length, the width and the depth, pick the shape and the kind of bottom, and the estimate below works out the gallons. Then take that number to the free calculator.

Rough measurements are fine. This is the same shape-and-depth estimate the app uses when you set up a pool.

Straight sides, square corners

Lengthft

Widthft

The usual inground

Shallow end depthft

Deep end depthft

Estimated volume

14,137 gallons

450 sq ft of water × 4.20 ft average depth

An estimate, not a measurement. If you know your pool’s real volume — from the builder, the manual, or a previous fill — use that instead.

Why guessing costs you money

Every amount poolcntrl gives you is worked out from your volume: the gallons, how far the reading has to move, and the strength of the product. So a wrong volume makes every amount wrong by the same share. If your guess is a fifth too high, you buy and pour a fifth too much of everything, every time. If it is too low, the doses fall short and the water never quite gets where it should.

The best number is one you already have

If the builder, the installer or the owner’s manual gave you a volume, use it. So does a fill you watched on a water meter. An estimate from measurements is the next best thing, and the one below is the same shape-and-depth estimate the app uses when you set up a pool.

Measuring without getting it wrong

Shape: Freeform is for a kidney, a lagoon or any curvy outline. Measure the longest and the widest points, even across water that isn’t there. The estimate already allows for the curve.
Depth: Measure the water, not the wall. An above-ground pool’s wall stands above the waterline, so using the wall height makes the pool — and every dose — come out too big.
Bottom: the kind of floor changes the average depth more than most people expect. Pick “Shallow end, then deep” for the usual inground pool, “All one depth” for an above-ground pool, and “Deepest in the middle” for a sports bottom.
Rough is fine. A tape measure to the nearest foot or so is closer than most guesses, and you can change the number in the calculator any time.

If you are still not sure

The calculator still gives you a plan. In the app, a volume you are unsure of is a warning on the plan rather than a block: you get the amounts with a note to check the volume first, because the amounts can only be as right as the gallons behind them.

Have your volume already? Go straight to the free calculator and add your readings, or read how accurate we are.

Keep learning

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