Pool Stabilizer Calculator: How Much to Add?

Stabilizer helps protect your swimming pool’s chlorine from breaking down quickly under the harsh ultraviolet (UV) rays of the sun. But how much stabilizer do you need to add to your pool? That’s what I’m here to help you figure out. I built a calculator that you can use below and walk you through all the steps and other things to consider. Let’s get started.

Here are the steps you need to take:

Test Your Stabilizer Level

First, you need to test your current pool stabilizer level to figure out how much additional stabilizer to add, or on the flip side, how much pool water to replace if your stabilizer level is too high. More on that later.

You can use a simple test kit to test your pool water. If you don’t see a test kit with “stabilizer” on the label as one of the tests, look for cyanuric acid (CYA). That’s the proper name for stabilizer.

The ideal level for stabilizer is 30-50 ppm for chlorine pools and 60-80 ppm for saltwater pools. Hot tub CYA levels should be pretty low, around 30 ppm. If your cyanuric acid level is too low, your chlorine will burn up quickly in the sun. If it’s too high, though, your chlorine won’t be very effective. Too much stabilizer will lock up the chlorine, preventing it from combining with the water’s contaminants and disinfecting the pool. So, keeping your CYA level in the right range is important.

For more details on this chemical, you can bookmark my articles on how to use cyanuric acid in your pool and pool stabilizers 101.

Measure Your Pool Volume

Once you have a reading on your current stabilizer level, the next step is to measure your pool volume (how many gallons of water are in your pool). I embedded my calculator below and linked it above if you don’t already have this number for your pool.


Select Your Stabilizer Form

Once you have those readings and calculations, it’s time to select the form of stabilizer you want to use. Stabilizer typically comes in two forms: granules and liquid stabilizer. Which form you choose is totally up to you; there isn’t much of a performance difference from my experience.

Calculate How Much Stabilizer to Add (or Water to Replace)

Alright, now it’s time to put everything together and do the final calculations. Enter your stabilizer preference (if you’re using granules, you can measure ounces by weight or volume), pool volume, current stabilizer level, and desired stabilizer level.

If you want to raise your stabilizer level, my calculator will spit out how many ounces (oz) you need to add. If you need to lower your stabilizer level, the calculated value will be the percentage of pool water you need to replace with fresh water to dilute everything. For example, if you get a value of “45.2,” that means you need to replace 45.2% of your current pool water with fresh water.

Make sense? Let’s get to calculating!


Hopefully, you got what you needed! You can check out my articles on pool maintenance tasks and pool chemistry for more info on dialing in the chemical levels of your pool.

Questions? Let me know.

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