Calculator
Pool Volume Calculator
Every chemical dose, every turnover calculation and every equipment sizing decision starts with one number: how many gallons of water the pool holds. Enter the dimensions and get the volume, plus the average depth used in the math.
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ft
ft
ft
Result
19,200 gallons
Use this figure for every chemical dose. Round down rather than up when dosing.
- Average depth
- 5.0 ft
- Shape factor
- 7.5
- Surface area
- 512 sq ft
- Litres
- 72,672 L
How this is calculated
- Volume = length x width x average depth x a shape factor, in US gallons.
- Shape factors: 7.5 for rectangles and squares, 5.9 for round and oval pools, 7.0 for kidney and freeform shapes.
- Average depth = (shallow-end depth + deep-end depth) / 2. For a pool with a sharp hopper slope, measure the depth at the break point and average the three readings instead.
- Results are rounded to the nearest gallon; for dosing, round down to stay conservative.
Figures follow commonly published residential pool references and are guidance, not a substitute for testing your own water. Always follow the product label and add one chemical at a time.
Frequently asked
- How many gallons is a typical residential pool?
- Most residential in-ground pools hold between 13,000 and 25,000 gallons. A 16x32 ft rectangle averaging 5 ft deep is about 19,200 gallons; a 12x24 ft rectangle at the same depth is about 10,800 gallons.
- Why does the shape factor change the result?
- The factor accounts for how much of the bounding rectangle the water actually fills. A round or oval pool fills roughly 79% of its bounding box, so it uses 5.9 instead of 7.5.
- Does a spa or attached water feature count?
- Yes, if it shares plumbing with the pool. Calculate the spa separately and add the two volumes together before dosing, since chemicals circulate through both.
- How accurate does the volume need to be?
- Within about 10% is fine for routine dosing. Precision matters most for shocking, stabilizer and salt, where over-dosing cannot be undone without draining water.
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