Pool volume calculator: how many gallons is my pool?
Multiply the surface area by the average water depth to get cubic feet, then multiply by 7.48 for US gallons. A 16 × 32 ft pool that runs from 3.5 to 8 feet deep holds about 22,023 gallons; a 24 ft round pool with 4.5 feet of water holds about 15,228.
Inputs used by this calculator
Pool Volume Calculator uses the fields below. The starting values reproduce the page example; replace them with values from the same units and time period before using the result.
| Input | Starting example | Accepted value | How it is used |
|---|---|---|---|
| Pool shape | Rectangle or square | Rectangle or square · Round · Oval | Supplies the pool shape quantity used by the published equation or result breakdown. |
| Length (ft) | 32 | 0 to 500 | Supplies the length (ft) quantity used by the published equation or result breakdown. |
| Width (ft) | 16 | 0 to 500 | Supplies the width (ft) quantity used by the published equation or result breakdown. |
| Diameter (ft) | 24 | 0 to 500 | Supplies the diameter (ft) quantity used by the published equation or result breakdown. |
| Water depth, shallow end (ft) | 3.5 | 0 to 50 | Supplies the water depth, shallow end (ft) quantity used by the published equation or result breakdown. |
| Water depth, deep end (ft) | 8 | 0 to 50 | Supplies the water depth, deep end (ft) quantity used by the published equation or result breakdown. |
| Fill rate (gallons per minute) | 8 | 0.1 to 10000 | Supplies the fill rate (gallons per minute) quantity used by the published equation or result breakdown. |
Why pool volume matters
Chlorine, shock, pH adjusters and algaecide are all dosed by volume, usually per 10,000 gallons on the label. Pump and filter sizing, heater sizing and the water bill for filling all depend on it too. A good estimate keeps you from wasting chemicals or under-treating the water.
Rectangular pools
Multiply length by width for the surface area, then by the average depth. For a sloped floor, the average depth is the shallow depth plus the deep depth divided by 2.
gallons = length × width × average depth × 7.48Round and oval pools
For a round pool, the surface area is π times the radius squared, or π × diameter² ÷ 4. Oval above-ground pools are close to an ellipse, whose area is π × length × width ÷ 4. Pool guides often round these to diameter² × depth × 5.9 for round pools, which is the same formula with the constants multiplied together.
round: gallons = π × d² ÷ 4 × depth × 7.48oval: gallons = π × L × W ÷ 4 × depth × 7.48Measuring depth correctly
Measure the water depth, not the wall height. Above-ground pools are usually filled to about 6 inches below the top rail, so a 52-inch wall holds about 46 inches of water. In an in-ground pool, measure at the shallow end and at the deepest point of the deep end.
Gallons, liters and cubic feet
A US gallon is exactly 231 cubic inches, so a cubic foot (1,728 cubic inches) holds 7.48052 gallons. One gallon is 3.785 liters, and a cubic meter is 264.17 gallons. The calculator shows all three so you can match product labels from any country.
How long it takes to fill
Divide the gallons by the hose flow rate in gallons per minute. A typical garden hose gives 5 to 10 gallons per minute, so a 20,000-gallon pool can take 33 to 67 hours. Time a 5-gallon bucket to measure your own flow rate, and check with your water utility before filling: some offer pool-fill rates or delivery by truck.
Water in common pool sizes
| Pool | Water depth | US gallons | Liters |
|---|---|---|---|
| Round above-ground, 15 ft | 4 ft | 5,288 | 20,016 |
| Round above-ground, 24 ft | 4.5 ft | 15,228 | 57,646 |
| Oval above-ground, 15 × 30 ft | 4.5 ft | 11,897 | 45,036 |
| In-ground rectangle, 16 × 32 ft | 3.5 to 8 ft | 22,023 | 83,365 |
| In-ground rectangle, 20 × 40 ft | 3.5 to 8 ft | 34,410 | 130,257 |
| Plunge pool, 8 × 14 ft | 5 ft | 4,189 | 15,857 |
Frequently asked questions
How do I calculate how many gallons are in my pool?
Multiply length × width × average depth in feet, then × 7.48. Use π × diameter² ÷ 4 for the area of a round pool.
How many gallons is a 24 ft round pool?
About 15,228 gallons with 4.5 ft of water (a 52-inch wall).
How do I find the average depth of a sloped pool?
Add the shallow-end and deep-end depths and divide by 2. For a pool with a large flat deep area, a weighted average is more accurate.
How many gallons are in a cubic foot?
7.48052 US gallons, because a gallon is 231 cubic inches and a cubic foot is 1,728.
How long does it take to fill a pool with a hose?
Gallons ÷ hose flow in gallons per minute. At 8 gallons per minute, 20,000 gallons takes about 42 hours.
Why does my chemical dose depend on gallons?
Pool chemical labels give doses per 10,000 gallons or similar. Follow the product label and the CDC's healthy-swimming guidance for safe handling.
What to keep in mind
Average depth assumes the floor slopes evenly from shallow to deep. Steps, benches, a hopper-shaped deep end and rounded corners change the true volume; a water meter reading during filling gives the exact figure.
Results are rounded for display in US format, with money in dollars and cents; CSV exports keep full calculation precision. This is a calculation summary, not an official certificate.