How to use the pool volume calculator
- Pick your pool shape: rectangle, round (circular), oval or kidney (approximate).
- Enter the dimensions in feet -- length and width, or diameter for a round pool.
- Choose depth: a single constant depth, or a shallow end and deep end (the calculator averages them for you, the standard pool-industry method).
- Read the gallons, liters and cubic feet below. No signup, no email -- everything runs in your browser.
How many gallons is my pool? The formula
Volume (cu ft) = surface area (sq ft) × average depth (ft). Gallons = cubic feet × 7.48. Liters = cubic feet × 28.317.
Worked example: a 32 x 16 ft rectangular pool at a constant 5 ft depth. Volume: 32 × 16 × 5 = 2,560 cu ft. Gallons: 2,560 × 7.48 = 19,149 gallons (72,491 liters).
How do I measure average depth?
Most pools aren't a single depth end-to-end -- they slope from a shallow end to a deep end. The standard method (used by Pentair's own pool volume calculator and recommended by Leslie's Pool Supply, which cites CDC guidance on measuring pool depth) is:
Average depth = (shallow end depth + deep end depth) ÷ 2.
Example: a shallow end of 3 ft and a deep end of 9 ft averages to 6 ft. A 30 x 15 ft pool at that average depth holds 2,700 cu ft, or 20,196 gallons. Choose "Shallow & deep end" above to use this directly -- no manual averaging needed.
Pool volume by shape
| Shape | Formula | Worked example | Result |
|---|---|---|---|
| Rectangle | L × W × avg depth × 7.48 | 32 × 16 ft, 5 ft deep | 19,149 gal |
| Round (circular) | π × (diameter ÷ 2)² × avg depth × 7.48 | 24 ft diameter, 4.5 ft deep | 15,227 gal |
| Oval | L × W × (π÷4) × avg depth × 7.48 | 30 × 15 ft, 5 ft deep | 13,218 gal |
| Kidney (approximate) | 0.45 × (width A + width B) × length × avg depth × 7.48 | 32 ft long, widths 10/16 ft, 5 ft deep | 14,003 gal |
The round formula is identical to pi × radius² × depth -- it's just the standard circle-area formula. The oval formula treats the pool as an ellipse (area ≈ length × width × π/4), a widely-used approximation, not an exact fit for every oval pool's true curve. The kidney formula (width A and width B are the pool's two widest points, measured across each "lobe") is a published industry approximation, not an exact fit -- kidney pools have no single standard formula since their shape varies so much; for a more precise number, split the pool into a rectangle plus part-circles (or other simple shapes) and add up each section's volume.
Gallons to liters
1 US gallon ≈ 3.7857 liters. The calculator shows both units for every result, computed from the same cubic-feet figure -- so gallons and liters always agree with each other and with the volume shown. The 19,149-gallon rectangular example above is 72,492 liters.
Why 7.48 gallons per cubic foot?
NIST Handbook 44 (the US reference standard for weights and measures) publishes 7.48 US gallons per cubic foot -- rounded from the exact 7.4805 (since 1 US gallon is defined as exactly 231 cubic inches). This calculator uses the more precise 7.48 rather than the 7.5 some pool-industry calculators round to for simplicity, so results here run very slightly lower than a 7.5-based estimate for the same dimensions.
Out of scope: this calculator estimates volume only (gallons, liters, cubic feet) -- it does not calculate salt or chlorine dosing, which depends on current chemical readings and product strength.
Other calculators
- Pouring a concrete deck or patio around your pool? Try the cubic yard calculator.
Frequently asked questions
How many gallons is my pool?
It depends entirely on shape, size and depth -- there's no single number. For a common in-ground size, a 32 x 16 ft rectangular pool averaging 5 ft deep holds about 19,149 gallons (72,491 liters). A 15 ft round above-ground pool at 4 ft deep holds roughly 5,287 gallons. Enter your own measurements above for an exact figure.
How do I calculate pool volume in gallons?
Find the surface area for your pool's shape (in sq ft), multiply by the average depth (ft) to get cubic feet, then multiply by 7.48 (US gallons per cubic foot). For the 32 x 16 ft, 5 ft-deep rectangle above: 32 x 16 x 5 = 2,560 cu ft, x 7.48 = 19,149 gallons.
How do I measure average depth?
Most residential pools have a shallow end and a deep end rather than one constant depth. The standard pool-industry method is average depth = (shallow depth + deep depth) / 2. For a pool with a 3 ft shallow end and a 9 ft deep end, average depth = (3 + 9) / 2 = 6 ft -- a 30 x 15 ft pool at that average depth holds about 20,196 gallons. Choose "Shallow & deep end" in the calculator above to use this method directly.
What is the formula for a round (circular) pool?
Volume = pi x (diameter / 2)^2 x average depth x 7.48, the same as any circle's area times depth. A 24 ft diameter round pool at 4.5 ft average depth works out to pi x 12^2 x 4.5 = 2,036 cu ft, or about 15,227 gallons.
Oval and kidney pool volume: how are they calculated?
An oval pool is estimated as an ellipse: length x width x (pi / 4) x average depth x 7.48 -- pi/4 is about 0.785, the standard ellipse-area approximation. A 30 x 15 ft oval at 5 ft deep holds about 13,218 gallons. Kidney pools have no single standard formula -- their curved, asymmetric shape varies too much -- so this calculator uses the industry-standard approximation published by Leslie's Pool Supply and Hunker: 0.45 x (width A + width B) x length x average depth x 7.48, where width A and width B are the pool's two widest points. A 32 ft long kidney pool with widths of 10 ft and 16 ft at 5 ft deep comes out to roughly 14,003 gallons -- treat this as a starting estimate, and for a more accurate number, split the pool into simpler shapes (e.g. a rectangle plus part-circles) and add up each piece.
Gallons to liters: how do I convert my pool volume?
Multiply gallons by 3.7857 (liters per US gallon), or let the calculator show both at once. The 19,149-gallon rectangular example above is about 72,492 liters.
Why does this calculator use 7.48 gallons per cubic foot instead of 7.5?
NIST Handbook 44 (the US reference for weights and measures) gives 1 cubic foot = 7.48 US gallons, rounded from the exact value of 7.4805 (since 1 US gallon is defined as exactly 231 cubic inches). Some pool-industry calculators round further to 7.5 for simplicity -- this calculator uses the more precise 7.48 figure.
How much water does it take to fill an average backyard pool?
A typical in-ground rectangular pool (roughly 32 x 16 ft, averaging 5 ft deep) takes about 19,149 gallons to fill, while a mid-size round above-ground pool (15 ft diameter, 4 ft deep) takes roughly 5,287 gallons. Actual fill time depends on your hose or fill line's flow rate, not just the volume.
Does this calculator handle salt or chlorine dosing?
No -- this tool covers volume only: cubic feet, gallons and liters. Chemical dosing (salt, chlorine, pH adjusters) depends on your pool's current readings and the specific product, so it belongs on a dedicated dosing calculator, not a general volume estimator.
Do I need to sign up, and is my data saved anywhere?
No. Enter your pool shape, dimensions and depth directly -- there is no signup and no email required. Your measurements are saved only in your own browser (so they are there next time you open this page on the same device); nothing is sent to our servers.