ContractorHandbook

How Many Gallons in a 22 Ft Round Pool?

Water in the pool

12,313 gallons

Round, 22 ft across, filled to a 52 in wall, which is 4.33 ft. Flat bottom, so the average depth is the wall height.

Filling this pool on a garden hose takes 1.1 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.

It does not stop at a number.

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.

average depthshallowdeeplength, ftsurface area x average depth x 7.48 = gallons
A pool with two depths is worked as one average depth, which is close enough for water and exactly how the chemical and turnover numbers are derived. Volume in cubic feet times 7.48 is gallons, and everything else on the page follows from that one figure.

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 diameter22 ft
  • Width22 ft
  • Shallow end depth4.33 ft
  • Deep end depth4.33 ft
  • Fill rate8 gal/min
  • Turnover target8 hours

Water in the pool12,313 gallons

Filling this pool on a garden hose takes 1.1 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 area380.1 sq ftpi r squared on the diameter
Average depth4.33 ftmidpoint of shallow and deep
Volume1,646 cu ft7.48 gallons in each
Water weight51.3 tons102,689 lb
Fill time25.7 hoursat 8 gallons a minute
Pump for turnover25.7 gal/minwhole volume once in 8 hours
Heater to raise 10 degrees1,027,000 BTU8.34 BTU per gallon per degree
Liquid chlorine for a 10 ppm shock0.99 gal12.5 percent, sold in gallon jugs, so buy 1
Salt to reach 3,200 ppm329 lb9 bags at 40 lb, from zero

The material list this produces

Water, gallons12,313
Liquid chlorine 12.5 percent, gal1
Salt, 40 lb bags9
Pump, gal/min26

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.

DiameterWater in the poolSurface areaFill time
8 ft1,629 gallons50.3 sq ft3.4 hours
12 ft3,664 gallons113.1 sq ft7.6 hours
15 ft5,724 gallons176.7 sq ft11.9 hours
18 ft8,243 gallons254.5 sq ft17.2 hours
21 ft11,219 gallons346.4 sq ft23.4 hours
24 ft14,654 gallons452.4 sq ft30.5 hours
27 ft18,546 gallons572.6 sq ft38.6 hours
30 ft22,896 gallons706.9 sq ft47.7 hours
33 ft27,704 gallons855.3 sq ft57.7 hours

What else matters here

12,313 gallons, and this is the size where the fill stops being an afternoon job. Twenty six hours on a hose at eight gallons a minute is more than a day of continuous water, which is the first practical reason to phone the water utility rather than uncoil the hose.

It is also the size where chemistry gets cheap per gallon and expensive per trip. A 10 ppm shock is about a gallon of 12.5 percent liquid chlorine, so you are finally buying in the unit the product is sold in. Salt for a chlorine generator is 329 pounds from zero, which is nine forty pound bags and a load your car will feel.

Twenty two feet is an awkward diameter to buy for. Liners, covers and solar blankets are stocked thickest at 18, 24 and 27 feet, and a 22 is often a special order with a longer wait. Worth knowing before the old liner splits in July rather than after.

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.

Can I fill this from a hose?

You can, and it takes about twenty six hours of continuous water. Two things make that worth a phone call first. Many utilities sell a bulk fill by tanker that arrives in an hour, and many will credit the sewer portion of a pool fill if you tell them before rather than after, because the water never reaches the sewer. On a private well, twenty six hours of continuous draw is enough to pull a shallow well down, so fill it in stages.

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.

Different numbers?

The pool volume calculator takes any dimensions you like and hands back the same list.

Other common sizes