Pool Volume Calculator
Every chemical dose, equipment size, and water bill starts with one number: how many gallons your pool holds. Enter your pool’s shape and dimensions to get gallons, liters, and cubic feet, then turn that volume into practical answers: how long the fill takes at your hose rate, and exactly how much chlorine to add for your target ppm.
Average depth:
Fill time
Chlorine dose
Dose = volume x ppm / product strength. Always add chemicals per the product label and retest before swimming.
Pool volume formulas by shape
Rectangle: length x width x average depth x 7.48 = gallons. Round: pi x radius^2 x average depth x 7.48. Oval: pi x (length/2) x (width/2) x average depth x 7.48. Kidney: length x width x average depth x 0.585 x 7.48, where 0.585 is the industry-standard area factor for the curved shape. Average depth for a sloped floor is (shallow + deep) / 2.
Worked example
A 32 x 16 ft rectangle, 3 ft shallow and 8 ft deep: average depth = 5.5 ft, surface = 512 sq ft, volume = 2,816 cu ft x 7.48052 = 21,065 gallons (79,740 liters). At an 8 GPM hose the fill takes 21,065 / 480 = 43.9 hours. To raise free chlorine by 2 ppm with 65% cal-hypo: 2 x 79,740 L = 159,480 mg pure / 0.65 = 245,354 mg of product = 8.7 oz.
Why volume accuracy matters
Every chlorine dose is ppm x gallons: a 20% volume error is a 20% dosing error. Undershooting leaves algae alive; overshooting wastes chemical and can bleach liners. Equipment sizing works the same way: pumps and filters are rated by turnover against gallons. Measure from the water surface, not the top of the wall, and for freeform pools break the shape into rectangles and ovals and add the sections.
What competing calculators miss
Most pool volume tools cover rectangle, round, and oval, then abandon you at the useful part. None compute fill time from your hose rate, and none convert the volume into a chlorine dose for your actual product strength. Kidney-shaped pools, some of the most common residential shapes, are missing from the basic tools entirely. This page does volume, fill time, and dosing in one pass.
Pool volume FAQs
How many gallons are in a 16x32 pool?
About 21,000 gallons at a 5.5 ft average depth (32 x 16 x 5.5 x 7.48). Shallower pools run closer to 15,000; deeper ones approach 25,000. Enter your depths above for your number.
How do I calculate average depth?
For a gradual slope: (shallow + deep) / 2. For a sharp drop-off, treat the shallow and deep sections as separate pools, compute each volume, and add them.
How long does it take to fill a pool?
Hours = gallons / (GPM x 60). A 21,000-gallon pool at 8 GPM takes about 44 hours; at 12 GPM about 29 hours. Enter your hose rate above.
How much chlorine do I add per 10,000 gallons?
It depends on the product: about 2 oz of 65% cal-hypo or 11 fl oz of 10% liquid chlorine raises 10,000 gallons by 1 ppm. Enter your target ppm and product above for the exact dose.
Does a kidney pool hold less than a rectangle?
Yes, about 58.5% as much for the same bounding dimensions: the 0.585 factor accounts for the curved cutouts. A 32x16 kidney at 5.5 ft averages about 12,300 gallons versus 21,065 for the rectangle.
Related calculators
More home and yard math in Home Improvement Calculators.