How Many Gallons in a 12 Ft Round Pool?
Water in the pool
2,116 gallons
Round, 12 ft across, filled to a 30 in wall. Flat bottom, so the average depth is the wall height.
When the figures look right, the pool water and chemical list downloads as a real PDF with your business details on it, built inside your own browser. Nothing you type is uploaded anywhere.
How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Pool shapeRound
- Length or diameter12 ft
- Width12 ft
- Shallow end depth2.5 ft
- Deep end depth2.5 ft
- Fill rate8 gal/min
- Turnover target8 hours
Water in the pool2,116 gallons
| Surface area | 113.1 sq ftpi r squared on the diameter |
|---|---|
| Average depth | 2.5 ftmidpoint of shallow and deep |
| Volume | 282.7 cu ft7.48 gallons in each |
| Water weight | 8.8 tons17,640 lb |
| Fill time | 4.4 hoursat 8 gallons a minute |
| Pump for turnover | 4.4 gal/minwhole volume once in 8 hours |
| Heater to raise 10 degrees | 176,000 BTU8.34 BTU per gallon per degree |
| Liquid chlorine for a 10 ppm shock | 0.17 gal12.5 percent, sold in gallon jugs, so buy 1 |
| Salt to reach 3,200 ppm | 57 lb2 bags at 40 lb, from zero |
The material list this produces
| Water, gallons | 2,116 |
|---|---|
| Liquid chlorine 12.5 percent, gal | 1 |
| Salt, 40 lb bags | 2 |
| Pump, gal/min | 5 |
Diameter compared
Same wall height as this page, at every diameter the round pool shelf comes in. Water goes up with the square of the diameter, so the jump from 24 to 27 feet costs more water than the jump from 8 to 15.
| Diameter | Water in the pool | Surface area | Fill time |
|---|---|---|---|
| 8 ft | 941 gallons | 50.3 sq ft | 2 hours |
| 12 ft | 2,116 gallons | 113.1 sq ft | 4.4 hours |
| 15 ft | 3,305 gallons | 176.7 sq ft | 6.9 hours |
| 18 ft | 4,759 gallons | 254.5 sq ft | 9.9 hours |
| 21 ft | 6,478 gallons | 346.4 sq ft | 13.5 hours |
| 24 ft | 8,461 gallons | 452.4 sq ft | 17.6 hours |
| 27 ft | 10,708 gallons | 572.6 sq ft | 22.3 hours |
| 30 ft | 13,220 gallons | 706.9 sq ft | 27.5 hours |
| 33 ft | 15,996 gallons | 855.3 sq ft | 33.3 hours |
What else matters here
2,116 gallons, and the diameter is doing all of it. A 12 foot pool is one and a half times the width of an 8 foot pool and holds more than twice the water, because the surface goes up with the square of the diameter while the depth stays put. That relationship is the reason the comparison table below is worth reading before you buy rather than after.
Four and a half hours to fill on a hose. That is still one afternoon, but it is long enough that it is worth starting before you finish leveling, not after, because the pool has to be sitting on its final spot before any water goes in. A partly filled pool cannot be moved and cannot be shimmed.
The dose is small and easy to overshoot. A 10 ppm shock here is about a sixth of a gallon of 12.5 percent liquid chlorine, so the jug gets measured out rather than poured. The same goes for anything sold by the scoop. Read the label dose per ten thousand gallons and take a fifth of it.
What this calculator assumes
- A cubic foot of water is 7.48 gallons and a gallon weighs 8.34 pounds. Those two numbers do all the work on this page.
- Average depth is taken as the midpoint of the shallow and deep ends. That is exact for a pool with one straight slope between them and slightly generous for a pool with a flat shallow shelf and a hopper, which is the safer way for it to be wrong when you are buying chemicals.
- A round pool uses the diameter and ignores the width. An oval is figured as an ellipse, which is length times width times pi over four, not as a rectangle.
- Turnover is the time the pump takes to move the whole volume once. Eight hours is the common residential target and some health codes for public water are stricter, so check yours before you size a commercial pump off this.
- Liquid chlorine trade percent is defined so that one gallon of it raises ten thousand gallons of water by that many parts per million. One gallon of 12.5 percent raises 10,000 gallons by 12.5 ppm, which is where the dose row comes from rather than a chart.
- Salt is figured from zero to 3,200 ppm, which is the middle of the range most chlorine generators want. A pool that already has salt in it needs a test first, because salt only leaves with the water.
Questions people ask
Is that the number printed on the box?
It is the same basis. A manufacturer quotes the pool filled to the top of the wall, which is what this page computes. In the yard you fill to the middle of the skimmer mouth, roughly six inches down, so the water actually in it lands about ten percent under the printed figure. Both numbers are useful: buy the cover and the liner off the printed one, and dose chemicals off the real one.
Where does the chlorine dose come from?
Liquid chlorine trade percent is defined so that one gallon of it raises ten thousand gallons of water by that many parts per million. One gallon of 12.5 percent raises 10,000 gallons by 12.5 ppm. The row on this page is the gallons for a 10 ppm shock at that strength, worked from the volume rather than read off a chart, which is why it moves when you change the size.
Is a 12 ft round big enough to swim in?
It is a cooling off pool, not a swimming pool. At 12 feet across with a 30 inch wall you can sit, float and play, and you cannot swim a stroke. If swimming is the point, the jump worth making is to an 18 foot with a 48 or 52 inch wall, which is the size the table below shows as nearly four times the water.
The pool volume calculator takes any dimensions you like and hands back the same list.