Pool Chemistry Calculator
Calculate a measured addition of liquid chlorine, dry chlorine or salt, or scale any manufacturer label dose to your pool volume and desired change.
How the pool chemistry calculator works
One part per million in pool water is one milligram of substance per liter of water. The calculator converts the pool volume to liters, multiplies it by the requested concentration increase and then divides by the active fraction of the selected product.
Liquid chlorine also needs solution density because a percentage by weight describes active mass, while the final dose is normally measured by volume. Dry chlorine is reported by mass. Pool salt uses the same ppm mass balance and corrects for the entered purity.
Formulas
- Required active mass (mg) = pool liters × requested increase (mg/L).
- Liquid product (mL) = active mass ÷ [strength fraction × density (g/mL) × 1,000 mg/g].
- Dry product (g) = active mass ÷ [available-chlorine fraction × 1,000 mg/g].
- Salt product (kg) = active mass ÷ purity fraction ÷ 1,000,000 mg/kg.
- Scaled label dose = label amount × (pool volume ÷ label volume) × (desired change ÷ label change).
Checked examples
| Pool and target | Product | Calculated addition |
|---|---|---|
| 10,000 US gal; raise FC by 3 ppm | 10% by weight; density 1.16 g/mL | 979 mL ≈ 33.1 US fl oz |
| 10,000 US gal; raise FC by 3 ppm | 65% available chlorine | 174.7 g ≈ 6.16 oz by weight |
| 10,000 US gal; raise salt by 2,200 ppm | 99.5% pure salt | 83.70 kg ≈ 184.5 lb |
| 20,000 US gal; desired change twice the label change | 12 fl oz per 10,000 gal | 48 US fl oz |
Limits and safe use
- This calculator estimates an addition; it does not prescribe the target concentration. Use the equipment manufacturer, product label and applicable local public-health guidance to choose targets.
- Percentages may be stated as ingredient concentration, available chlorine, trade percent or weight/volume. Enter only the basis requested by the selected mode.
- Sunlight, cyanuric acid, temperature, contaminants and circulation affect sanitizer demand after dosing.
- pH adjustment is intentionally excluded because acid/base demand is not linear and depends on total alkalinity, borates, aeration and the specific product.
- Round practical additions according to the product’s measuring instructions, distribute as directed, circulate and retest before adding more.
Frequently asked questions
Does this calculator tell me the correct chlorine target?
No. It calculates the product quantity after you provide the current and target readings. Required ranges depend on the pool, sanitizer system, stabilizer level, jurisdiction and current conditions.
Can I use household bleach?
Only use a product whose label permits the intended pool application. Fragrances, thickeners, additives and unknown strength can make a household product unsuitable.
Why does liquid chlorine require density?
The concentration is entered by weight, but the dose is displayed by volume. Density connects grams of solution to milliliters, so a generic assumption would reduce accuracy.
Can the label scaler handle alkalinity or calcium products?
Yes, when the current product label gives a dose, reference pool volume and expected change using consistent units. The calculator scales that exact instruction without assuming a chemical formulation.
Related calculators
Use the Pool Volume Calculator to estimate gallons from pool dimensions, the Percentage Calculator for concentration changes, or the Volume Calculator for general shapes.