Calculate your pool volume accurately. Support for rectangular, oval, and circular pools. Essential foundation for precise chemical dosing and water treatment.
Start by choosing your pool's shape: rectangle, oval, round, or freeform. Measure with a tape at the water line, not the coping, and record length and width in the same unit you plan to enter (feet or meters). The hardest input is average depth, not a single spot reading. For a pool that slopes from a shallow to a deep end, take the depth at the shallowest point and the deepest point, add them, and divide by two. For a pool with a long flat shallow section before the slope, weight your average toward the depth that covers the most surface area, or split the pool into two zones and add their volumes. For round pools, measure the diameter across the true center. Freeform pools: estimate an average length and average width that 'box in' the curves. Accurate measurements here cascade into every chemical dose you will ever calculate, so spend an extra minute getting depth right rather than guessing.
The math depends on shape. Rectangle: length × width × average depth × 7.48 = US gallons (the 7.48 converts cubic feet to gallons; in metric, length × width × depth in meters × 1000 = liters). Round: diameter × diameter × average depth × 5.9 = gallons. Oval: length × width × average depth × 6.7 = gallons. Worked example, rectangular pool 32 ft × 16 ft, shallow end 3 ft and deep end 8 ft: average depth = (3 + 8) ÷ 2 = 5.5 ft. Volume = 32 × 16 × 5.5 × 7.48 = 21,066 gallons, about 79,750 liters. In metric, a 10 m × 5 m pool averaging 1.7 m deep = 10 × 5 × 1.7 × 1000 = 85,000 liters (≈ 22,500 US gallons). Note that 1 cubic meter equals exactly 1,000 liters, so metric dosing reduces to simple multiplication.
Volume is the foundation under every other calculator on this site, so an error here multiplies through chlorine, acid, alkalinity, and stabilizer doses alike. Overestimating volume by 20% means you under-treat and algae wins; underestimating means you over-dose and risk corroding equipment or irritating swimmers. The most common mistake is using the maximum depth instead of the average, which can inflate a sloped pool's volume by 30% or more. A second frequent error is measuring the deck dimensions rather than the actual water surface. If you are unsure, verify with the 'chemical rise' method: add a known dose, retest, and back-calculate the true volume from how far a parameter moved. Round your final figure to the nearest few hundred gallons or liters and save it, because for chemical safety it is better to slightly underestimate volume than overestimate it. Re-measure if you change the water line, add an attached spa, or install a tanning ledge.
All chemical dosages are based on the total amount of water in your pool. An incorrect volume leads to severe over-dosing or under-dosing of chemicals.
Measure the average length, average width, and average depth. Treat it as a rectangle for a close estimate, or use the 'chemical rise' method for precision.
It gives a close estimate from standard geometric formulas for rectangular, round, and oval pools. For freeform or irregular shapes the result can vary 5-10% from the true volume, so for chemical dosing round to the nearest few thousand gallons and confirm with a test kit after dosing.
A typical residential in-ground pool holds about 10,000 to 25,000 gallons (roughly 38,000 to 95,000 liters). A standard 16x32 ft rectangular pool with an average depth of 5 ft holds close to 19,000 gallons, which is why 20,000 gallons is a common reference size for dosing.
Yes, in the Metric system, 1 cubic meter is exactly 1,000 liters. This makes dosing calculations very straightforward for global pool owners.