How Many Gallons in a 15x30 Pool?
Water in the pool
15,149 gallons
Rectangle, 30 ft by 15 ft, shallow end 3 ft, deep end 6 ft, so the average depth is 4.5 ft.
Filling this pool on a garden hose takes 1.3 days of continuous water. Most water utilities sell a bulk fill, and some will not meter a pool fill through the sewer charge if you call first, which is worth more than the hose.
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 shapeRectangle
- Length or diameter30 ft
- Width15 ft
- Shallow end depth3 ft
- Deep end depth6 ft
- Fill rate8 gal/min
- Turnover target8 hours
Water in the pool15,149 gallons
Filling this pool on a garden hose takes 1.3 days of continuous water. Most water utilities sell a bulk fill, and some will not meter a pool fill through the sewer charge if you call first, which is worth more than the hose.
| Surface area | 450 sq ftlength by width |
|---|---|
| Average depth | 4.5 ftmidpoint of shallow and deep |
| Volume | 2,025 cu ft7.48 gallons in each |
| Water weight | 63.2 tons126,335 lb |
| Fill time | 31.6 hoursat 8 gallons a minute |
| Pump for turnover | 31.6 gal/minwhole volume once in 8 hours |
| Heater to raise 10 degrees | 1,263,000 BTU8.34 BTU per gallon per degree |
| Liquid chlorine for a 10 ppm shock | 1.21 gal12.5 percent, sold in gallon jugs, so buy 2 |
| Salt to reach 3,200 ppm | 405 lb11 bags at 40 lb, from zero |
The material list this produces
| Water, gallons | 15,149 |
|---|---|
| Liquid chlorine 12.5 percent, gal | 2 |
| Salt, 40 lb bags | 11 |
| Pump, gal/min | 32 |
Deep end compared
The shallow end stays where this page has it and the deep end moves. Average depth is the midpoint of the two, so every foot you add at the deep end adds half a foot of average depth and the water goes up with it.
| Deep end | Water in the pool | Average depth | Pump for turnover |
|---|---|---|---|
| 4 ft | 11,782 gallons | 3.5 ft | 24.5 gal/min |
| 5 ft | 13,465 gallons | 4 ft | 28.1 gal/min |
| 6 ft | 15,149 gallons | 4.5 ft | 31.6 gal/min |
| 7 ft | 16,832 gallons | 5 ft | 35.1 gal/min |
| 8 ft | 18,515 gallons | 5.5 ft | 38.6 gal/min |
What else matters here
15,149 gallons on 450 square feet. A 15 by 30 is the small end of a standard inground rectangle and it is a good shape for a narrow lot, because the length is where the swimming happens and the width is what the yard is short of.
The average depth is doing the quiet work in that number. Three feet at one end and six at the other averages four and a half, and the engine takes the midpoint, which is exact for a pool with one straight slope between the ends. A pool with a flat shallow shelf and a hopper holds slightly less than this, so the figure errs on the generous side, which is the safe direction when you are buying chemicals.
Thirty two hours on a hose and a 32 gallon a minute pump for an eight hour turnover. Both are ordinary for a pool this size, and the pump number is the one to check against the filter rather than the pump alone, because a filter that cannot pass the flow makes the pump work harder for less water moved.
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
Why is the average depth 4.5 and not 4.5 everywhere?
It is the midpoint of the shallow and the deep end, three and six. That is exactly right for a pool with one straight slope running between them, and slightly generous for a pool with a flat shallow shelf and a deep hopper, which holds a little less. Generous is the safer way for it to be wrong, because it means a chemical dose worked from this page is never short.
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.
Why is the salt figure from zero?
Salt only leaves a pool with the water, through splash out, backwash and a leak. It does not evaporate. So the bag count here is what an empty pool needs to reach 3,200 ppm, and a pool that has run on salt before needs a test first or you will overshoot it. Adding salt is easy and taking it out means draining water.
The pool volume calculator takes any dimensions you like and hands back the same list.