Pool calculator
Type in your latest water test and pool size. You get every dose, in the order to add them, for chlorine, pH, alkalinity, calcium, stabilizer and salt.
Your pool
Test results
What you have on the shelf
Your dosing plan
- Lower pH Add13.4 fl oz muriatic acid 31.45%pH 7.8 → 7.5. Pour slowly in front of a return jet. Details
- Raise calcium hardness Add9 lb calcium chloride (77%)CH 250 → 300 ppm. Pre-dissolve; it gets hot. Details
- Raise free chlorine Attention1.2 qt (38 fl oz) liquid chlorine 10%FC 1.5 → 3.5 ppm (minimum 2.3 at CYA 30). Details
The explanation is written by an AI model from your numbers. The doses above come from fixed chemistry and don’t change.
What happens if I add…
Already poured something in, or reading a label? Enter the product and amount to see what it does to your water.
| Free chlorine | – |
Starts from the pool size and test results above. Changes appear after the product has fully dissolved and circulated.
Quick dose references (per 10,000 gal)
| To change | Add |
|---|---|
| FC +1 ppm | 10.2 fl oz liquid chlorine 12.5% |
| FC +1 ppm | 20.7 fl oz bleach 6% |
| TA +10 ppm | 1.4 lb baking soda |
| CH +10 ppm | 1.2 lb calcium chloride 77% |
| CYA +10 ppm | 13.5 oz stabilizer |
| Salt +1,000 ppm | 83 lb pool salt |
pH doses aren’t linear: they depend on alkalinity and stabilizer, so use the calculator above or the acid calculator.
Chemical safety: read the product label first and follow it where it differs from this page. Add acid to water, never water to acid. Never mix chlorine products with acid or with each other, not even in a bucket. Add one chemical at a time with the pump running, wait at least 30 minutes (acid and chlorine: until the next test), and retest before topping up.
How this pool calculator works
Every amount comes from the chemistry of the product, not a lookup table. One part per million in 10,000 US gallons is 37.85 grams of the active ingredient, so a dose is simply the change you want × your volume ÷ the product’s strength. pH is harder: how much acid it takes depends on your alkalinity and stabilizer, so the calculator models the carbonate buffer in your water and solves for the dose that lands on the target.
Targets follow CDC guidance for home pools (pH 7.0–7.8, free chlorine at least 1 ppm, or 2 ppm when stabilizer is used) and the ranges pool professionals work to under the PHTA/ANSI water-quality standards. Free chlorine is scaled to your stabilizer level, which is why the target moves when you change CYA.
Why the order matters
Alkalinity is the buffer that resists pH change. Fix it first and your pH dose lands where you expect. pH comes next because chlorine works best near 7.5. Calcium and stabilizer are slow, stable numbers you set once or twice a season. Chlorine goes last because it’s the number you’ll top up every day or two.
Your numbers are saved on this device
Your pool size and last test are remembered in your browser so every calculator on the site starts with them. Nothing is uploaded unless you press the explain button. Clear or learn more.
Every calculator
- FCChlorine calculatorLiquid, bleach, cal-hypo, dichlor or tabs, matched to your CYA.
- SLAMShock calculatorShock level from stabilizer, combined chlorine or algae.
- pH−Lower pH (acid)Muriatic acid or dry acid, dosed to your alkalinity.
- pH+Raise pHSoda ash, borax or aeration, with the alkalinity side effect.
- TAAlkalinity calculatorBaking soda to raise it, acid and aeration to lower it.
- NaOClLiquid chlorine & bleachFl oz of liquid chlorine or bleach for your pool.
- NaClSalt calculatorBags of salt to reach your chlorinator’s target.
- CYAStabilizer (CYA) calculatorAdd cyanuric acid, or work out how much to drain.
- LSILSI calculatorWill your water etch plaster or scale the heater?
- SPAHot tub chemical calculatorSmall-volume dosing for spas and hot tubs.
- GALPool volume calculatorGallons or liters for any shape, plus fill time.
- SIZEPool gallons chartGallons for common round, oval and rectangle pools.
- GPMPump size calculatorFlow rate for your turnover target and pipe size.
- FT²Filter size calculatorSand, cartridge or DE area for your flow rate.
- BTUHeater size calculatorGas heater or heat pump output and heat-up time.
- INEvaporation calculatorNormal water loss vs. a leak, from your weather.
- CHARTPool chemistry chartIdeal levels for every test, with sources.
- HELPPool water troubleshooterDescribe the problem, get a step-by-step fix.
Questions pool owners ask
In what order should I add pool chemicals?
Adjust total alkalinity first, then pH, then calcium hardness, then stabilizer (CYA), and chlorine last. Alkalinity changes how far a dose of acid or base moves pH, so fixing it first stops you chasing pH. Add one chemical at a time with the pump running and let it circulate before the next.
How accurate is a pool chemical calculator?
The math here is exact chemistry for the volume you enter, but the result can only be as good as your test and your volume estimate. Test strips are often off by a whole color block; a drop-based (titration) kit is far more precise. Add about three quarters of a big dose, circulate, retest and then finish.
What are the ideal pool chemical levels?
CDC recommends pH 7.0–7.8 and at least 1 ppm free chlorine (2 ppm if you use stabilizer). Most pool pros aim for pH 7.4–7.6, total alkalinity 60–120 ppm, calcium hardness 200–400 ppm for plaster, and CYA 30–50 ppm for chlorine pools or 60–80 ppm for salt pools. See the full chart for every test.
Why does free chlorine depend on stabilizer?
Cyanuric acid holds most chlorine in a reserve form that doesn’t sanitize quickly. The more CYA, the more free chlorine you need for the same killing power. A common rule of thumb is to keep free chlorine at about 7.5% of your CYA as a minimum.
Is it safe to swim right after adding chemicals?
Wait until the chemical has fully circulated and a retest shows free chlorine and pH back in range. After liquid chlorine or acid that is usually 30 minutes to a few hours; after a shock, wait until chlorine falls back to your normal level. Always follow the product label.