Pool chemistry calculator
Enter your water test numbers and pool volume below and get the exact amount of each chemical to add — chlorine, pH, alkalinity, stabilizer, calcium, and salt.
Chlorine (free chlorine)
pH
Total alkalinity
Cyanuric acid (CYA)
Calcium hardness
Salt
How much chemical should I add to my pool?
It depends on three things: how far your reading is from the target, your pool’s volume in gallons, and the strength of the product you’re using. Each calculator below does that math from first principles, so the amount is specific to your pool — not a generic “add a cup” rule of thumb.
Get your pool volume right first
Every dose scales directly with volume, so an accurate gallon count matters most. For a rectangle: length × width × average depth × 7.48. Round and oval pools use 5.9 and 6.7 instead of 7.48. If you’re unsure, measure carefully — a 20% error in volume is a 20% error in every dose.
Add chemicals in the right order
Balance alkalinity first, then pH, then calcium, then stabilizer and salt, and chlorine last. Add one chemical at a time with the pump running, wait and circulate, and re-test before adding more. Never mix chemicals — especially acid and chlorine.
Ideal ranges
| Level | Target | Notes |
|---|---|---|
| Free chlorine | 1–3 ppm (scale with CYA) | Higher CYA needs higher FC |
| pH | 7.2–7.8 (ideal 7.4–7.6) | Comfort + chlorine efficiency |
| Total alkalinity | 60–120 ppm | Lower end for salt pools |
| Cyanuric acid (CYA) | 30–50 ppm | 60–80 for saltwater |
| Calcium hardness | 200–400 ppm | Higher for plaster |
| Salt | 2,700–3,400 ppm | Check your generator’s manual |
Frequently asked questions
Is this pool calculator free?
Yes, completely free. For saved history, reminders, trend insights, and the exact order to add things, the DoseMyPool iOS app is free too.
Does it work for saltwater pools?
Yes — use the salt calculator for your generator’s target, and the others for chlorine, pH, alkalinity, CYA, and calcium just like a chlorine pool.
How accurate is it?
The math is derived from first principles (stoichiometry, plus a carbonate-equilibrium model for pH and alkalinity) and matches the DoseMyPool app. Results are estimates — always follow product labels and re-test.
Related calculators & guides
Get exact doses, saved and on schedule
DoseMyPool remembers your pool, gives the safe order to add things, and reminds you to test — free on the App Store.