Pool Volume Calculator
This pool volume calculator tells you how much water your swimming pool holds. Pick a rectangle, round, oval, or kidney pool, enter the size, and set the depth, either one average depth or the shallow and deep ends. You'll get the pool's volume in US gallons, Imperial gallons, and liters, plus the surface area, with the formula shown. It's the quick way to size up dosing, heating, and how long it'll take to fill.
- 4 pool shapes
- Average depth handled
- Gallons and liters
- Surface area too
- Formula shown
Last updated June 16, 2026 4 shapes, average depth Reviewed by the Calcowa math team
Enter positive numbers to see the pool volume.
Show volume in all units
V = L × W × D
What is pool volume?
Pool volume, or pool water volume, is the amount of water a swimming pool holds when it's full. You find it by taking the pool's surface area and multiplying by the average depth. The shape sets how you work out the surface area, but the rest is the same: area across the top, times how deep the water sits. The answer usually gets reported in gallons or liters, because that's what dosing and heating math needs.
Knowing the volume isn't just trivia. Chlorine, salt, and other chemicals are dosed per gallon or per liter, and a heater is sized to the water it has to warm. Get the volume wrong and you'll either over-treat or under-treat the water.
Pool volume formula by shape
Every pool volume formula is the surface area times the average depth, D. Here's how the four shapes work out their surface area, where L is length, W is width, and W1 and W2 are the two widths of a kidney pool.
| Pool shape | Formula | Typical pool |
|---|---|---|
| Rectangle | V = L × W × D | Straight-sided pool |
| Round | V = π × (d/2)² × D | Circular above-ground pool |
| Oval | V = π × (L/2) × (W/2) × D | Oval or oblong pool |
| Kidney / freeform | V = 0.45 × (W1 + W2) × L × D | Curved, two-width pool |
A round pool is a short, wide cylinder, so the cylinder volume calculator gives the same result for a flat-bottom pool.
How do you calculate pool gallons?
To calculate pool gallons, find the volume in cubic feet and multiply by 7.48, which this tool does for you. Here's the routine:
- 1
Pick the pool shapeRectangle, round, oval, or kidney.
- 2
Measure at the surfaceMeasure the length and width, or the diameter, across the top.
- 3
Set the depthUse one average depth, or enter the shallow and deep ends.
- 4
Read gallons or litersThe result gives the volume in both right away.
Average depth, shallow to deep
Most pools aren't one flat depth, so this is where people slip up. A pool with a shallow end and a deep end uses the average of the two: add the shallow depth to the deep depth and divide by two. A pool that's 3 feet at the shallow end and 8 feet at the deep end averages 5.5 feet, not 8. Choose the shallow-to-deep option above and the calculator averages it for you, which keeps your gallons honest. If the floor slopes oddly or has a hopper, the average is still close enough for dosing.
Pool volume in gallons and liters
Pool chemicals come dosed per gallon or per liter, so the conversion matters. One cubic foot of water is 7.48 US gallons, and one cubic meter is 1,000 liters. Watch the gallon type, because a UK or Canadian Imperial gallon is about 20 percent bigger than a US one, and a dosing chart written for one won't match the other. This tool shows US gallons, Imperial gallons, and liters together, so you can read whichever your products use.
Olympic and average pool sizes
An Olympic swimming pool is 50 meters by 25 meters and at least 2 meters deep, so it holds at least 2,500 cubic meters, which is 2.5 million liters or roughly 660,000 US gallons. A typical backyard in-ground pool is far smaller, usually 15,000 to 30,000 US gallons, or about 55,000 to 115,000 liters. If you're comparing quotes for chemicals or a heater, those ranges are a useful sanity check against the number you get above.
Kidney and irregular pool shapes
A kidney or freeform pool curves, so there's no clean rectangle to measure. The pool trade uses a tidy estimate: 0.45 times the sum of the two widest widths, times the length, times the average depth. It isn't perfect for every curve, but it lands close. For a truly odd shape, split it into a rectangle plus a half circle, work out each part above, and add them. That split-and-add trick handles almost any irregular pool.
Volume units and accuracy
Calcowa shows the pool volume in US gallons, Imperial gallons, liters, cubic meters, and cubic feet at once. The round and oval math uses the full value of pi, so the result is accurate for dosing, heating, and fill-time planning.
| Unit | Best for | Good to know |
|---|---|---|
| US gallons (gal) | US pool chemistry | 1 ft³ = 7.48 US gal |
| Imperial gallons | UK and Canada pools | 1 imp gal = 1.201 US gal |
| Liters (L) | Metric pools | 1 m³ = 1,000 liters |
| Cubic meters (m³) | Large and Olympic pools | 1 m³ = 264 US gal |
| Cubic feet (ft³) | Surface and turnover math | 1 ft³ = 28.3 liters |
Frequently asked questions
Is pool volume measured in gallons or liters?
Both are common. US pools are sized in US gallons, the UK and Canada often use Imperial gallons or liters, and most of the world uses liters or cubic meters. This calculator shows all of them, so it doesn't matter which your products list.
Multiply the pool's surface area by its average depth. For a rectangle that's length times width times average depth, and for a round pool it's pi times the radius squared times the depth. The calculator above does all four pool shapes and converts to gallons and liters for you.
Work out the volume in cubic feet, then multiply by 7.48 to get US gallons, which this tool does automatically. A pool 30 by 15 feet at an average depth of 5 feet holds about 16,800 US gallons. Pick the shape, enter the size, and read the gallons straight off.
Add the shallow-end depth to the deep-end depth and divide by two. A pool that's 3 feet at the shallow end and 8 feet at the deep end has an average depth of 5.5 feet. Choose the shallow-to-deep option above and the calculator averages it for you.
Find the volume in cubic meters, then multiply by 1,000, since one cubic meter is 1,000 liters. This tool shows the liters beside the gallons, so you don't have to convert anything. A 50,000-liter pool is a fairly typical family size.
An Olympic pool is 50 meters long, 25 meters wide, and at least 2 meters deep, so it holds at least 2,500 cubic meters, which is 2.5 million liters or about 660,000 US gallons. That's why competition pools take so long to fill.
Measure the length and the two widest widths, then use the pool-industry estimate: 0.45 times the sum of the two widths times the length times the average depth. It isn't exact for every curve, but it's the accepted way to size a kidney pool. Pick Kidney above to run it.
A typical residential in-ground pool holds somewhere between 15,000 and 30,000 US gallons, or roughly 55,000 to 115,000 liters. The exact figure depends on the shape and how deep the deep end goes, so it's worth measuring yours.
More volume tools
Sizing other water containers? These pair well with the pool volume calculator.
Water and fuel tank capacity.
Cylinder volumeRound pools and pipes.
Volume calculatorEvery 3D shape in one tool.
Rectangular prism volumeStraight-sided pools and boxes.
Area calculatorSurface area of the pool footprint.
Area of a circleRound pool surface area.
Sizing a different pool?
Switch pool shapes above, or browse the full geometry hub.