An estimate from the standard volume formulas. Irregular shapes and attached spas vary; for an exact figure, measure in sections and add them.
You need
18,563gallons
Average depth 5.5 ft. Keep this number on the pool's record so every dose starts from it.
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Pool volume in gallons is length times width times average depth times 7.5 for a rectangular pool, or diameter times diameter times average depth times 5.9 for a round pool. Average depth is the shallow end plus the deep end, divided by two. This calculator does the math from your measurements.
How it works
Using the pool volume calculator
Why gallons is the first number you need
Every dose after this one scales with how much water you are treating. Salt targets, chlorine adjustments, and alkalinity corrections are all per-gallon. Guess the volume and every chemical calculation that follows is off by the same margin, so it is worth getting once and writing down.
How the math works
Multiply length by width by average depth in feet, then by 7.5 for a rectangular or square pool (a cubic foot of water holds about 7.48 gallons). Round and oval pools use 5.9 instead, which accounts for the curved shape. Average depth is the shallow-end depth plus the deep-end depth, divided by two.
Measure once, keep it on the pool record
If you service pools for a living, you should not recompute volume on every visit. Record each pool's gallons once and keep it with the pool's specs, so the number is there when you log readings or dose. PoolBoss stores gallons on the pool record alongside its sanitizer type and surface.
FAQ
Common questions
How do I calculate the volume of my pool?
Measure length, width, and the depth at the shallow and deep ends in feet. Average the two depths. For a rectangular pool, multiply length by width by average depth by 7.5 to get gallons. For a round pool, multiply diameter by diameter by average depth by 5.9. Oval pools also use the 5.9 multiplier.
What is the average depth of a pool?
Average depth is the shallow-end depth plus the deep-end depth, divided by two. A pool that is 3 feet at the shallow end and 8 feet at the deep end has an average depth of 5.5 feet. Use the average depth in the volume formula, not either single measurement.
How many gallons is a 15 by 30 foot pool?
A 15 by 30 foot rectangular pool with an average depth of 5 feet holds about 16,875 gallons (15 times 30 times 5 times 7.5). Change the average depth and the number moves with it, which is why measuring both ends matters.
Why does pool volume matter for chemicals?
Chemical doses are calculated per gallon of water. The amount of salt, chlorine, or baking soda you add depends directly on how many gallons you are treating. An accurate volume keeps you from under-dosing, which wastes a visit, or over-dosing, which can damage equipment and irritate swimmers.
