Pool Chemical Calculator

Enter your pool size in gallons and your test readings. Get the exact amount of each chemical to add — no guessing.

gallons

Free Chlorine

Ideal: 1–3 ppm (or about 7.5% of your CYA). Adjust chlorine last.

Current (ppm)
Target (ppm)
Product

pH

Ideal: 7.4–7.6. Balance alkalinity first — it controls how pH behaves.

Current
Target
Acid (to lower) strength

Total Alkalinity

Ideal: 80–120 ppm. Adjust this first of all.

Current (ppm)
Target (ppm)
Acid (to lower) strength

Calcium Hardness

Ideal: 200–400 ppm (plaster) or 175–225 ppm (vinyl/fiberglass).

Current (ppm)
Target (ppm)

Cyanuric Acid (Stabilizer)

Ideal: 30–50 ppm. Dissolves slowly — allow a few days and retest.

Current (ppm)
Target (ppm)

Safety — read before adding anything

Adjust in this order

  1. Total Alkalinity — it buffers pH, so set it first (80–120 ppm).
  2. pH — bring into 7.4–7.6 once alkalinity is stable.
  3. Calcium Hardness — top up to range if low.
  4. Cyanuric Acid — set stabilizer so the sun doesn't burn off your chlorine.
  5. Free Chlorine — adjust last, once everything else is dialed in.

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How the doses are calculated

What strengths these assume

Doses assume common product strengths: liquid chlorine as labeled (6–12.5%), cal-hypo 65–73%, dichlor 56%, muriatic acid 31.45% (with 20% and 15% options), baking soda (sodium bicarbonate) for alkalinity, soda ash (sodium carbonate) for raising pH, pool-grade calcium chloride for hardness, and cyanuric acid for stabilizer. Always check your product's label — strengths vary by brand.

Why pH and alkalinity doses are estimates

Acid demand depends on your alkalinity, calcium hardness, and water temperature, so pH and alkalinity adjustments are starting points, not exact guarantees. Add about two-thirds, run the pump, and retest before adding more. For lowering alkalinity, add the acid in one spot in the deep end with the pump off, then run the pump and aerate to bring pH back up.

Lowering calcium hardness or stabilizer

There's no chemical that removes calcium or cyanuric acid from pool water. The only practical way to lower them is to drain part of the pool and refill with fresh water. This calculator shows how much water to replace.

This tool gives starting-point estimates for standard pool chemicals based on your pool volume and readings. It is not a substitute for testing. Always test your water with a reliable kit before and after dosing, follow product label directions, and handle chemicals safely.