Pool number of gallons : getting it right


Well-known member
Feb 10, 2020
NJ (shore)
Pool number of gallons
My pool has a kidney shape. It is probably 3 feet deep in the shallow and 9 in the deep.

It's 32 feet long (around) and 20 large (depends from where as it is not a regular shape).

It's going deep pretty quickly when it starts to go deep probably around 13 feet from the steps in the shallow area.

I have calculated around 28.000 gallons. Does it seem about right ?


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Try running it through the Pentair calculator then use the chemistry way.

If you need to get an estimate of the amount of water in your pool you can use the calculator at the bottom of the old Pool math web page. You simply enter the pool dimensions and average depth and it gives you the gallons of water int he pool.

Pentair has a Pool Volume Calculator that lets you select from rectangular, oblong, round, and triangle shapes.

There is also a Chemical Way of Calculating Pool Volume using an alkalinity test kit, sodium bicarbonate or acid, and the formula.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Use PoolMath

So let's say you plug in your numbers to adjust pH and add the necessary acid. If you are using the right volume, you probably hit it. If you're off a little, you raise or lower the volume next time. Not a huge amount, maybe 500 or 1000 gallons. Eventually you'll hit the spot where you went too far, and you can back off halfway. At some point in time, your additions will always hit the target, and then you'll know.

This will also work with TA, if you're adding. Bleach is iffy, as the strength can vary with age and it is a consumable and a lot of the consumption depends on how sunny it is, how hot, how many people are in the pool, and how weak are their bladders. :mrgreen:
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