Pool Calculator
Calculate your pool's volume in gallons and liters from its shape, size and shallow/deep end depths — the number chemical dosing is based on.
How many gallons is my pool?
Every chemical dose, pump size and heating estimate for a pool starts from one number: its volume. The volume is surface area × average depth — and “average” is doing real work, because most pools slope. With a shallow and a deep end, the average of the two depths is the standard approximation.
Volume (cubic feet) = surface area × average depth · Gallons = cubic feet × 7.48 · Liters = cubic feet × 28.32
Example: a rectangular pool 20 × 10 ft, 4 ft at the shallow end and 6 ft at the deep end: average depth 5 ft, surface 200 sq ft, volume 1,000 cubic feet = 7,481 gallons (28,317 liters).
Surface area by shape
| Shape | Surface area |
|---|
| Rectangular | Length × width |
| Round | π × (diameter ÷ 2)² |
| Oval | π × (length ÷ 2) × (width ÷ 2) |
| Kidney / freeform | ≈ 0.45 × overall length × overall width (rough) |
Freeform pools are the honest limit of a formula: the 0.45 factor for a kidney shape is a planning figure, and your pool builder's stated volume — measured once, properly — beats any estimate for chemical work. This is a volume tool: no shopping list, no waste allowance, just the number the dosing charts ask for. Measure the water depth, not the wall height — the waterline sits a few inches below the coping, and those inches are not in the pool.
Frequently asked questions
Why average the shallow and deep ends?
Because a sloped floor means the pool is, geometrically, close to a wedge — and a wedge's volume is its surface times the mean of its end depths. For a constant-slope pool this is nearly exact; pools with a sharp hopper drop are a little deeper than the average suggests, usually by under 10%.
How accurate does the volume need to be for chemicals?
Within about 10% is fine for routine dosing — chlorine and pH products are dosed in ranges, not drops. If your test results never match the dose you added, the volume is the first suspect: re-measure rather than doubling chemicals.
What about a pool with a beach entry or sun shelf?
A tanning shelf displaces real volume: subtract roughly its area × its depth (about 1 ft of water over it) from the total, or measure that section as its own shallow “pool” and treat the remaining deep section separately, then add the two volumes.
How many liters is 10,000 gallons?
About 37,854 liters. The calculator shows both units at once — and swaps the headline order when you switch the Imperial/Metric toggle — because dosing products are labelled in gallons in the US and liters almost everywhere else.
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