Pool Chemical Calculator
Work out how much liquid chlorine, cal-hypo, dichlor, trichlor or salt to add to reach a target level.
About the Pool Chemical Calculator
Chlorine doses scale with pool volume and the rise you want: 1 ppm is 1 mg per litre. Liquid chlorine strength is quoted as trade percent (grams of available chlorine per 100 mL), so 1 US gallon of 12.5% liquid raises a 10,000-gallon pool by about 12.5 ppm.
Solid products are rated by % available chlorine by weight. Never mix chlorine products with each other or with acid; add chemicals to water, not water to chemicals, and keep children away.
The formula
Litres of liquid = Δppm × pool litres ÷ (strength × 10⁶); grams of solid = Δppm × litres ÷ 1000 ÷ strength
Worked example
Example: Liquid chlorine to add = 0.92 L (0.24 US gal, 31 fl oz)
- Inputs: Pool volume: 17,000; Volume in: US gallons; Add: Liquid chlorine / bleach; Product strength: 14 % available chlorine; Current level: 1 ppm; Target level: 3 ppm.
- Formula: Litres of liquid = Δppm × pool litres ÷ (strength × 10⁶); grams of solid = Δppm × litres ÷ 1000 ÷ strength
- Result: Liquid chlorine to add = 0.92 L (0.24 US gal, 31 fl oz)
Things to keep in mind
- Follow the product label; this doesn't replace testing your water.
Questions people ask
What free chlorine level?
Commonly 1–4 ppm; higher if cyanuric acid is high.
What is shocking?
Raising chlorine high enough to kill algae and break down contaminants; the target depends on CYA.