This pool volume calculator, often searched as a pool water calculator or "how many gallons is my pool", works out how much water a swimming pool holds. Choose the pool shape, enter the inside dimensions and average water depth, and it returns US gallons, litres, cubic feet and cubic metres. It suits rectangular, round, oval and freeform pools, including above ground pools.
MEASUREMENT & CALCULATION GUIDE
How to calculate swimming pool volume in gallons and litres
A pool volume calculator, also called a pool water calculator, estimates how much water a swimming pool holds from its shape, inside dimensions and average water depth. Pool capacity is the starting point for chemical doses, pump turnover, heater size and heating cost, so a measured value is far more reliable than the pool's advertised size. The tool reports US gallons, litres, cubic feet and cubic metres.
Rectangular: length × width × average depth × 7.48052 = US gallons
Round: π × radius² × average depth × 7.48052 = US gallons
Oval: π ÷ 4 × length × width × average depth × 7.48052 = US gallons
How many gallons is my pool?
It depends on the shape, size and depth, and the table below shows worked examples. A 12 × 24 ft rectangular pool with a 4 ft average depth holds about 8,600 gallons (12 × 24 × 4 × 7.48), while a 15 ft round pool at the same depth holds about 5,300 gallons. Enter your own measurements in the calculator for an exact estimate.
Examples of pool size and approximate volume| Pool | Average depth | US gallons | Litres |
|---|
| 15 ft round (above ground) | 4 ft | 5,290 | 20,000 |
| 24 ft round (above ground) | 4 ft | 13,540 | 51,200 |
| 30 ft round (above ground) | 4 ft | 21,200 | 80,100 |
| 12 × 24 ft rectangle | 4 ft | 8,620 | 32,600 |
| 15 × 30 ft rectangle | 5 ft | 16,830 | 63,700 |
| 15 × 30 ft oval | 4.5 ft | 11,900 | 45,000 |
| 20 × 40 ft rectangle | 5.5 ft | 32,900 | 124,600 |
| 10 × 5 m rectangle (metric) | 1.5 m | 19,800 | 75,000 |
These are worked examples, not averages for every pool. Real volume changes with the actual dimensions, depth and features, so measure your own pool.
Average swimming pool volume in gallons
There is no reliable average that fits every pool. Residential in-ground pools commonly fall somewhere in the range of 10,000 to 25,000 gallons, and round above ground pools from 15 to 30 ft hold roughly 4,000 to 26,000 gallons depending on diameter and depth. Use the actual inside dimensions and average water depth of your pool rather than a general average.
Pool volume in litres
Measure in metres, multiply length × width × average depth to get cubic metres, then multiply by 1,000 for litres. A 10 × 5 m pool with a 1.5 m average depth holds 75 m³, which is 75,000 litres or about 19,800 US gallons. To convert gallons to litres, multiply by 3.785.
Oval, round and above ground pools
Select the shape that matches your pool. For round and above ground pools, use the inside diameter and the depth of the water rather than the wall height. For an oval pool the calculator uses π ÷ 4 × length × width, and freeform pools are approximated as ovals, so irregular curves, benches and steps can cause differences from the actual capacity.
Measuring in inches
The calculator accepts feet or metres. If you measured in inches, divide by 12 to get feet, so a 180 inch diameter is 15 ft and a 54 inch depth is 4.5 ft. The guide to measuring a pool explains where to take each measurement.
Where to use your pool volume
COMMON QUESTIONS
About Pool Volume Calculator
How many gallons is my pool?
It depends on the shape, size and average depth. For a rectangular pool, multiply length × width × average depth (in feet) by 7.48. For a round pool, use π × radius × radius instead of length × width. A 15 ft round pool with a 4 ft average depth holds about 5,300 gallons, a 24 ft round pool at 4 ft holds about 13,540 gallons and a 15 × 30 ft rectangular pool at 5 ft holds about 16,800 gallons. Enter your own measurements above for your exact figure.
How do I calculate pool gallons?
For a rectangular pool, multiply length × width × average depth (all in feet) and then by 7.48. A 30 × 15 ft pool with a 5 ft average depth holds about 16,800 gallons (450 × 5 × 7.48). For a round pool, use π × radius × radius in place of length × width, and for an oval pool use π ÷ 4 × length × width.
How do I calculate pool volume in litres?
Measure in metres. Length × width × average depth gives cubic metres, and one cubic metre is 1,000 litres. A 10 × 5 m pool with a 1.5 m average depth holds 75 m³, or 75,000 litres (about 19,800 US gallons). Switch the calculator to metres and it does the conversion for you. To convert gallons to litres, multiply by 3.785.
How many litres are in a swimming pool?
There is no single figure. A 4.5 m round above ground pool with 1.2 m of water holds about 19,100 litres, a 10 × 5 m pool at 1.5 m holds 75,000 litres and a small 6 × 3 m plunge pool at 1.3 m holds about 23,400 litres. Use the calculator in metres to get the litres for your own pool.
What is the average swimming pool volume in gallons?
There is no reliable average that fits every pool. Residential in-ground pools commonly fall somewhere in the range of 10,000 to 25,000 gallons, while round above ground pools from 15 to 30 ft hold roughly 4,000 to 26,000 gallons depending on diameter and depth. Because the spread is so wide, measure your own pool before using the figure for chemicals, equipment or heating.
How do I calculate the volume of an oval pool?
Use π ÷ 4 × length × width × average depth × 7.48 for US gallons. A 15 × 30 ft oval pool with a 4.5 ft average depth holds about 11,900 gallons. Select Oval in the calculator, or Freeform if the shape is irregular. Freeform pools are approximated as an oval, so treat the answer as an estimate.
Can I enter my pool dimensions in inches?
The calculator works in feet or metres, so convert inches to feet first by dividing by 12. A 180 inch diameter is 15 ft and a 54 inch water depth is 4.5 ft. For centimetres, divide by 100 to get metres.
How do I find the average depth of my pool?
If the floor slopes evenly from the shallow end to the deep end, add the two depths together and divide by two. A pool that is 3 ft at one end and 7 ft at the other averages 5 ft. If there is a long flat section or a sudden drop, work out each section separately.
Should I use maximum depth or wall height?
No. The deepest point and the wall height both overstate the volume, and any chemical dose based on them will come out too high. Use the average depth of the water, measured from the floor to the waterline.
Is a pool water calculator the same as a pool volume calculator?
Yes. People search for it as a pool water calculator, pool gallons calculator, pool size calculator or "how many gallons is my pool", but all of them ask the same question: how much water is in the pool. Enter the shape, dimensions and average depth to get gallons, litres and cubic metres.
Why does pool volume matter?
Nearly every treatment dose, from salt and chlorine to stabilizer, scales with the amount of water. If the volume is 20% too high, the dose will be about 20% too high as well. Once you know it, use it in the pool salt calculator, pool chlorine calculator or pool pump size calculator.
