Calculator Tools
Pool Volume Calculator
Calculate swimming pool volume in gallons and liters for rectangle, round, oval, kidney, and freeform pools, with chlorine, salt, and pH dosing.
Pool shape
Standard rectangular pool: length, width, and depth. The most common in-ground pool shape.
Unit system
Depth profile
Worked examples
Tap any example to load typical real-world pool dimensions into the calculator.
Pool chemistry dosing
Quick-reference doses scaled to your pool's US gallon volume. Always add chemicals in steps, dissolve granular doses in a bucket of water if the label requires, and retest before adding more.
Liquid chlorine (12.5% sodium hypochlorite)
36.2 fl oz
Raises free chlorine by 2 ppm
4.5 US cups (~1.07 L)
Cups + liters equivalents
10.5 fl oz per 10,000 gal per 1 ppm FC
Cal hypo shock (65% calcium hypochlorite)
25.9 oz
Shock dose to raise FC by 10 ppm
1.6 lb (~732.9 g)
Pounds + grams equivalents
1.5 oz per 10,000 gal per 1 ppm FC
Cyanuric acid (stabilizer)
67.2 oz
Adds 30 ppm of CYA
4.2 lb (~1,906 g)
Pounds + grams equivalents
13 oz per 10,000 gal per 10 ppm CYA
Pool salt (sodium chloride)
46.1 lb
Raises salinity from 0 to 3200 ppm (saltwater pool)
20.9 kg (~1.2 40 lb bags)
Kilograms + 40 lb bag count
8.35 lb per 10,000 gal per 1000 ppm salt
Soda ash (sodium carbonate) to raise pH
10.3 oz
Raises pH by about 0.2 (e.g. 7.2 to 7.4)
0.65 lb (~293.2 g)
Pounds + grams equivalents
6 oz per 10,000 gal per 0.2 pH
Muriatic acid (31.45% HCl) to lower total alkalinity
86.2 fl oz
Lowers total alkalinity by 20 ppm
10.8 US cups (~2.55 L)
Cups + liters equivalents
25 fl oz per 10,000 gal per 10 ppm TA
How the formulas work
- Average depth: for a sloped bottom, average the shallow-end and deep-end depths. This is the formula used by every pool industry training manual and is accurate within a few percent for a linear-bottom slope. A hopper or spoon bottom (deepest point only in one corner) is slightly less than the linear average; for a hopper pool, treat the deep-end value as the deepest point in the hopper.
- Rectangle: Length x Width x Average depth. The cleanest and most common formula.
- Round: pi x (D / 2) ^ 2 x Average depth. Use the water depth, not the wall height of an above-ground pool; an 18-foot above-ground pool with a 48-inch wall typically holds ~42 inches of water.
- Oval: (pi / 4) x Length x Width x Average depth. Equivalent to the area of an ellipse times the depth, and matches the formula used by the US Pool & Spa Industry training manual.
- Kidney:(Long length + Short length) x Width x 0.45 x Average depth. The 0.45 factor compensates for the inward curve at the kidney's waist.
- Freeform: Length x Width x Average depth x 0.85. Length and width are the bounding box; the 0.85 factor accounts for typical curve and edge loss in a freeform pool. For an unusually narrow lagoon shape, drop to 0.70; for a near-rectangular freeform, raise to 0.90.
- Unit conversions: 1 cubic foot = 7.4805 US gallons = 6.2288 imperial gallons = 28.317 liters. 1 cubic meter = 1000 liters = 264.17 US gallons.
How the dosing works
- Liquid chlorine: 10.5 fl oz of 12.5% sodium hypochlorite per 10,000 US gallons raises free chlorine by 1 ppm. The tool defaults to a 2 ppm raise; scale linearly for any other target.
- Cal hypo shock: 1.5 oz of 65% calcium hypochlorite per 10,000 US gallons raises FC by 1 ppm. The tool defaults to a 10 ppm shock dose; SLAM-level chlorination uses CYA + the Pool Math chart.
- Cyanuric acid: 13 oz per 10,000 US gallons raises CYA by 10 ppm. The tool defaults to a 30 ppm raise (a fresh-fill addition).
- Pool salt: 8.35 lb of sodium chloride per 10,000 US gallons raises salinity by 1000 ppm. The tool defaults to a fresh-fill raise from 0 to 3200 ppm for a saltwater pool.
- Soda ash (pH up): 6 oz per 10,000 US gallons raises pH by about 0.2 from a starting pH of 7.2.
- Muriatic acid: 25 fl oz of 31.45% HCl per 10,000 US gallons lowers total alkalinity by 10 ppm. The tool defaults to a 20 ppm reduction. Add slowly with the pump running and avoid the skimmer.
- Dosing is a quick estimate, not chemistry advice. Read product labels, follow local safety rules, and test water with a kit before and after every addition.
How to use
- Pick the pool shape: rectangle, round, oval, kidney, or freeform. The dimension fields change to match the shape.
- Choose the unit system (imperial feet + inches, or metric meters) and the depth profile (constant depth for a flat-bottom pool, or sloped for a shallow + deep end average).
- Type the dimensions. Imperial fields accept feet plus optional inches. For above-ground pools, enter the water depth, not the wall height.
- Read the Volume panel for US gallons, imperial gallons, liters, cubic feet, cubic meters, average depth, and the plan-view footprint area.
- Scroll down to the Pool chemistry dosing card for a quick-reference dose of liquid chlorine, cal hypo shock, cyanuric acid, pool salt, soda ash for pH, and muriatic acid for total alkalinity, all scaled to the pool's exact gallon volume.
- Tap a worked example (typical inground, Intex round above-ground, oval, kidney, freeform lagoon, metric inground, or spa) to preload realistic dimensions, or click Reset to restore the default example.
- Click Copy summary to copy the full result, including every unit conversion and every dosing line, into your notes or a maintenance log.
About this tool
Pool Volume Calculator computes the water volume of a swimming pool or spa for the five most common shapes (rectangle, round, oval, kidney, and freeform) and converts the result to US gallons, imperial gallons, liters, cubic meters, and cubic feet. Pick a shape, switch between imperial (feet + inches) or metric inputs, and choose a depth profile: constant depth for an above-ground or lap pool with a flat bottom, or sloped depth that averages the shallow-end and deep-end values for the standard linear-bottom slope used in residential inground pools. The math is the closed-form geometry every US pool industry training manual uses: rectangle is length times width times average depth, round is pi times the radius squared times depth, oval is the area of an ellipse (pi over four times length times width) times depth, kidney uses the (long length plus short length) times width times 0.45 factor from the Hayward and BioLab service guides, and freeform multiplies the bounding box by an 0.85 fill factor for typical curve and edge loss. Once the volume is known the tool prints a maintenance dosing chart scaled to the pool's exact US gallon volume: liquid chlorine (12.5% sodium hypochlorite) to raise free chlorine by 2 ppm, cal hypo (65%) to shock by 10 ppm, cyanuric acid stabilizer to raise CYA by 30 ppm, pool salt to raise salinity to 3200 ppm for a fresh-fill saltwater pool, soda ash to raise pH by about 0.2, and muriatic acid (31.45%) to lower total alkalinity by 20 ppm. Each dose is shown in both English (fl oz, oz, cups, lb) and metric (L, g, kg) and includes the underlying per-10,000 gallon formula so the reader can scale to a different target or active ingredient strength. Worked examples preload classic real-world pools: a 16-by-32 ft sloped-bottom inground, an 18 ft round Intex / Bestway above-ground at 42 in water, a 12-by-24 ft oval above-ground, a 28-foot kidney, a freeform 30 by 20 ft lagoon at 3 to 7 ft, a 10 by 5 m metric inground, and a round spa or hot tub. Useful for new pool owners, vacation rental hosts trying to estimate seasonal chemical budgets, pool service techs sanity-checking a route stop, real estate listings that need a volume number, and anyone who just wants to know 'how many gallons is my pool?' without measuring the inside of a vinyl liner. Dosing is a conservative starting point, not chemistry advice; always read the product label, dissolve granular chemicals in a bucket of water when the label requires, add in steps, and retest with a kit before adding more. Everything runs locally in your browser; the dimensions and water targets you enter are not uploaded.
Free to use. Works in your browser. No signup, no login.
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