How this calculator works
Choose your pool's shape — rectangular with a shallow and deep end, round, or oval — enter its dimensions in feet, and this calculator returns the volume in gallons, liters and cubic meters together. Rectangular pools use the average of the shallow and deep end depths; round pools use the circle-volume formula; oval pools use an ellipse-area approximation, which is accurate enough for chemical dosing and fill-time estimates on a typical rounded-rectangle or oval above-ground pool.
Knowing pool volume matters most for chemical dosing (chlorine, pH adjusters and algaecides are all dosed per gallon or per thousand gallons) and for estimating fill time from a garden hose or fill service. A small error in volume compounds into over- or under-dosing chemicals, so it's worth measuring depth at a few points for a sloped-bottom pool and averaging them rather than guessing.
The formula
Rectangular: volume = length × width × average depth, where average depth = (shallow + deep) ÷ 2Round: volume = π × radius² × average depthOval: volume = π × (length ÷ 2) × (width ÷ 2) × average depthGallons = cubic feet × 7.48052; liters = cubic feet × 28.316846592; cubic meters = cubic feet × 0.0283168465927.48052 US gallons per cubic foot is the standard published conversion. The liter and cubic-meter conversions follow directly from the exact international foot definition (1 ft = 0.3048 m), so all three unit conversions here are exact, not rounded approximations.
Worked example: a 32 ft × 16 ft rectangular pool, 3 ft to 8 ft deep
- Average depth: (3 + 8) ÷ 2 = 5.5 ft.
- Volume: 32 × 16 × 5.5 = 2,816 cubic feet.
- In gallons: 2,816 × 7.48052 ≈ 21,065 gallons.
- In liters: 2,816 × 28.316846592 ≈ 79,740 liters (about 79.7 cubic meters).
Frequently asked questions
Why is the oval formula an approximation?
A true oval pool's edge usually isn't a perfect mathematical ellipse — many are closer to a rounded rectangle. Treating it as an ellipse (π × half-length × half-width × depth) gives a volume close enough for chemical dosing and fill-time purposes; for an exact figure on an unusual shape, split the pool into a rectangle plus two half-circles and add the volumes separately.
How do I measure average depth accurately?
For a simple two-depth rectangular pool, average the shallow and deep measurements as this calculator does. For a pool with a more complex, continuously sloping bottom, measure depth at several evenly spaced points along the length and average all of them for a more accurate figure.
Why does chemical dosing depend on volume so much?
Chlorine, pH adjusters and algaecides are all labeled in amount per gallon (often per 10,000 gallons). Both too little and too much lead to real problems — too little allows algae and bacteria growth, too much can irritate skin and eyes or bleach pool liners and swimwear.
Does this include the volume above the pool's waterline?
No — enter your actual water depth, typically a few inches below the pool's structural rim, not the full wall height. Pools are never filled completely to the very top edge.
How long will my pool take to fill?
Divide the gallons figure by your hose or fill service's flow rate in gallons per hour. A typical garden hose delivers roughly 9 to 10 gallons per minute (around 540 to 600 gallons per hour), though actual flow varies with hose diameter and water pressure.