Pool Volume Calculator
Estimate pool gallons from shape, dimensions, and average depth before dosing chemicals.
Interactive calculator · Method POOL_VOLUME-2.0 · Last reviewed: 2026-10-02
Estimate pool volume from measured dimensions
Use pool shape, measured dimensions, and average depth to estimate gallons before sizing filters, planning water changes, or using any chemical-dosing label. Measure carefully and treat the result as a planning volume, not a lab reading.
Your inputs
Default worked example. Edit the inputs to calculate your scenario.
Default worked example
Rectangle surface area × (3 + 6)/2 ft average depth = 57.342 m³. One US gallon is exactly 3.785411784 liters.
How to use the calculator
Select rectangle, circle or oval. Enter measured dimensions and shallow/deep water depths in one unit. A circle uses diameter; an oval uses its full length and width. Switching feet/meters preserves the measured dimensions.
What the result means
Use the approximate water volume to describe the pool and compare capacity. The average-depth model fits a uniform or linearly sloped bottom. It does not supply chemical quantities.
Formula and units
Rectangle area = length × width. Circle area = π × (diameter/2)². Oval area = π × length/2 × width/2. Volume = area × (shallow depth + deep depth)/2. Convert cubic meters to liters by multiplying by 1000; divide liters by 3.785411784 for US gallons.
Worked examples
30 × 15 ft rectangular pool: Length (ft): 30 selected dimension unit; Width (ft): 15 selected dimension unit; Diameter for round pools: 24 selected dimension unit; Shallow depth: 3 selected dimension unit; Deep depth: 6 selected dimension unit; Dimension unit: ft; Shape: rect.
Example result: Pool volume: 15,148 US gal; Liters: 57,342 L; Cubic meters: 57.342 m³; Average depth: 4.5 ft.
16-foot round pool: Length (ft): 30 selected dimension unit; Width (ft): 15 selected dimension unit; Diameter for round pools: 16 selected dimension unit; Shallow depth: 4 selected dimension unit; Deep depth: 4 selected dimension unit; Dimension unit: ft; Shape: round.
Example result: Pool volume: 6,016 US gal; Liters: 22,774 L; Cubic meters: 22.774 m³; Average depth: 4 ft.
Limitations and common mistakes
Steps, benches, freeboard and irregular bottom geometry require separate segments or measured fill volume. Gallons here are US gallons. The exact geometric volume conversion is elementary unit arithmetic, not a dosing model.
Use diameter, not radius, for a circular pool. Measure water depth rather than the wall height. Do not add the shallow and deep depths without dividing by two.
Sources and assumptions
Volume conversion is mathematical; average-depth choice and actual geometry are user-entered approximations.
Method POOL_VOLUME-2.0; last formula review 2026-10-02. Sources and their supported claims. Calculation methodology.
NIST: length and volume conversions. One US gallon is 231 cubic inches; 231 × 0.0254³ × 1000 gives 3.785411784 liters. Shape formulas follow elementary geometry.